Go to http://store.steampowered.com/ and click on the "Get Steam now" button. Download that file and run it, and it will install Steam. Now, just run Steam, and it'll ask you to make an account. Enter your information, and follow any other steps it prompts you to take.
I purchased Portal 2 but accidently assigned the steam account to my sister's PSN account rather then mine. How, if possible, could I re-assign my steam account to my PSN account?
To create a Steam account you need to go the the Steam Powered website and go to Create A New Account. There will be a form to fill out and you'll get an email with a verification link that you need to click.
Yes, but it's free.
no you cant steam friends in an acount.
Yes, you need a Steam account to purchase and play Garry's Mod (GMod). The game is available exclusively on the Steam platform, where you can buy, download, and manage it. Additionally, having a Steam account allows you to access community features, mods, and multiplayer gameplay.
It is not possible to delete a Steam account. However, you may be able to contact Valve (the company behind Steam) and see what they can do. Contact link in the related links below.
The lower the digit count the older the account is.
no
Yes but games are not
yes
Absolutely! Your Steam account is accessible the same way that an email account is. Once you install Steam on a computer, you can log in with your own account and your entire game library will be available to you. You will need to install whichever games you want to play on the "new" computer, but your account/scores/achievements will all be the same on any computer through the Steam cloud. I personally have a few games installed on each of my two computers using the same account, and sometimes I log into my friend's Steam program so I can have my achievements there too!
You create a steam account and download the steam app