Hi there

You just bought Valheim, and what the heck do you do here ?
Valheim is a survival game, but less about making sure you are fed and such but more about exploring the world and basically being tough enough to be the boss.
This tutorial is for solo players but the basics are useful for MP as well.

You start the game for the first time by making a ‘toon’, avatar … a character, but this stage is all up to you, it makes no real impact on the game, just make what you want, and name the character.
You then need to make a world, or rather just randomly generate a seed or input one of your choosing, at this stage its not too impactfull, but on other runs you may want to control that seed a tad, to make sure the world aint too crazy.
There is a map seed generator, a easy google will result in the app, Valheim map generator.
I suggest for your first time to just random a seed and go with it… creating new worlds and characters is easy and free.

Ok, now you have been dropped into your world, literally, there was some text that had something about Odin, Valheim and blah blah…
You now find yourself in a circle of odd stones, in your rags and skivvies, owning a total of 1 torch.
A Bird is in your face, so press E to chat to it, it will tell you that you have to kill dangerous monsters that Odin wants got, but you are in rags and underwear… so you need to do some work before facing these bosses.
Then the bird poofs out of sight, but reappears on a stone with red markings, this is important as by pressing E on that stone will show you the location of the first boss, and teach you such stones will mark bosses.

Your first job is to collect materials, that torch aint gonna get you far though it does deal with the immediate enemies decently.
Look at the floor and pick up stones and sticks, run around the circle and look for berries or mushrooms, eating those will boost your HP and Stamina, and call the bird in to explain this as well.
Get a couple of sticks, you can punch saplings using left click of the mouse, the commands are shown in the bottom right of the screen.
Pressing Tab will bring up your inventory and the basic crafting… a club, a hammer and a axe.
A axe will let you fight and more importantly, chop down trees for wood, so lets go for that… then a club, as using your wood cutting tool as a weapon will drop its durability twice as fast.
Try keep resource equipment seperate from combat as both activities will deplete durability.

Run around and explore the area, the mini map at the top right will tell you if you are meadows, or an other biome, you want to stay in the meadows for now, the bird will warn you once if you stray into the black forest… its easy to see, the meadows has beech and birch trees with the occasional oak tree, the black forest has pine and fir trees… stay out of the black forest for now.
You should also look to nab any mushrooms and berries you can, and if attacked take mats off boars, necks (lizard looking critters) and greylings, food and the resin will come in handy.

Now it may be getting dark, this has a few issues, its hard to see, you get a cold debuff which is a slight stamina regen loss, so is getting wet.
You should think of setting up some basic homebase, least big enough to have a workbench and a bed inside, with some chests to keep stuff in.
You just need your hammer and the materials, wood at this stage of the game, craft a hammer if you havent already, and select it in the tool bar, you need a workbench to craft building parts so build a workbench which is in the crafting tab, near to where you want to make your home, then with a right click you can choose pieces to craft, a basic wall and roof tiles will do for now, maybe a door.
The workbench and bed need to be under shelter, which for now is under roof pieces, the bed on first interaction (pressing E) will claim the bed, then after it will let you sleep the night away.

You can get away with a basic 3 x 2 box and some roof pieces to cover the lot, you need a campfire so put that outside for now, campfires generate smoke and if not properly vented can make you take damage, and early game you aint rocking too much spare health.
The fire will not work in rain so you may need to place a roof piece over it to shelter from rain, and be careful you can catch on fire if you get too close, and the damage early game can be bad.
Once you have your basic box of a home, or you can take over abandoned buildings just need to repair that stuff or it will look broke, to repair simply select your hammer, right click for a menu and choose the hammer icon, left clicking will now repair, middle mouse will destroy any piece and right click will let you choose a piece.
Oh yeah, floor pieces do not count at roof at the wood stage, you need to use roof pieces to get shelter.

You may of killed few boars while roaming around, they drop meat and leather scraps, as well as a trophy.
You need to cook the boar meat to eat it, if you have your campfire and hammer handy you can sort this out easily, select hammer and select the cooking station under crafting, place the station over the campfire and you can cook the meat… If the meat is in your inventory, the station will auto accept all cookable items, if you want to cook a specific item either pack the other options away or put the item into your hotbar then you can press the specific number of that item to cook.

Food is dealt with in a odd manner, food types can be HP mostly, Balanced or Stamina, the little fork icon will let you know which is best for what. You can only eat one of any type, like one boar meat not two boar meat but you can eat one boar and one deer meat, you can only eat three food items at anytime… for example a good mix is a mushroom, or berry and two different types of meat for a good HP and some decent Stamina.
You cant die from not eating, you will remain at the base of 25 HP and low Stamina, but eating will boost your HP and Stamina to rather good levels, so you want to have 3 types of food handy when in dangerous terrain… at base even chopping a tree can be lethal if it falls on you, oh yeah trees can fall and hurt you, its the most common death for new players.

Hmm, your items at this stage may be low on durability, you can repair with no costs at the workbench but only items the bench or lower can craft, for now the workbench is good for all your equipment, just click on the hammer icon on the side of the crafting menu, it will be yellow when you have something to repair or dark when there is nothing to repair, make it a habit to run to your bench and repair everything before going out.

At this stage you have everything you need to explore the world, you should hunt boars for the leather so you can build a crude bow at the workbench, plus some wood arrows.
The bow will make it easier to hunt deers for a beginner, you can sneak (press CTRL by default) to sneak up to a deer and whack it, sneaking does take stamina and is a skill you skill up by using.
Getting an attack on a target that is not aware of you gives you a crit damage modifier, which does a decent chunk of damage.
Now its all on you, hunt deer and boars, gather berries and mushrooms, upgrade your stuff and workbench, and when you have some good kit and weapons, take on the first boss.
Good luck.