How to add TF2 to Steam library

In your steam window, when you have Library selected it will have your games listed.

Above the list should be a drop down menu that you can click, it probably is set on "Installed" since you only see Portal.

Change the option to "All Games" and it will list all the games that are bound to your account so you can install them.

If you want to play on the same PC:

Yes. Steam should recognise that the game is already installed. Failing that (which definitely works on games newer to Steam, but I'm unsure about older games like TF2), copy the contents of your SteamApps folder to his. (see the SteamApps\username instructions below)

If you want to play on seperate PCs:

Yes. Open your SteamApps folder. This will be depend on your operating system and be:

C:\Program Files\Steam\SteamApps

for 32 bit (older) Windows systems,

C:\Program Files (x86)\Steam\SteamApps

for 64 bit (newer) Windows systems, and

/Users/<username>/Library/Application Support/Steam/SteamApps

for Mac OS X systems.

You will need to copy all files who's name begins with "source" or "team fortress 2" from that folder on your PC to the folder on your brother's PC. There is also a file called winui.gcf which you will need to copy in there also.

Then follow the instructions in the below heading.

SteamApps\username folder instructions

You will also need to copy the <your steam username>\team fortress 2 folder inside your SteamApps folder to SteamApps\<your brothers steam username>\team fortress 2. If there are any folders beginning with source or winui in there as well, you should copy those also. Apart from required files for the game itself, these folders contain configuration and downloaded maps.

Notes

If you miss any individual files then they will be downloaded when Steam launches the game.

These instructions will not work for Windows to Mac, or Mac to Windows.