Log in to your Steam account.
Click the [Your username] link in the upper right hand corner and select Account Details.
Click on "+Add funds to your Steam Wallet" to select an amount and proceed to checkout.

I'm using one of these:
http://www.vpnanswers.com/wp-content...218923d317.png

Just put the card number in normally like you would with a credit card...

Also LOL thanks for posting the entire ****ing card now anybody can use it.

Good thing you didn't show the back cause then everyone would've been able to see the security code.

can you post a pic of the back of it? I need to see something on the back of it to make sure it's usable on Steam.

Yay, now do it click on the big fat add to cart button?

Uh... Yeah?

Just waiting for .NET Framework 4 to install.