If you have a Steam-compatible product, then you will need to activate that product in the program to use it with Steam. Steam is an online game portal that allows you to play against other people online. Primarily developed for the "Half Life" family of games, its use has since spread to other games as well. A Steam key is the key associated with your account when you activate a product. Therefore to get a steam keys, you must activate your purchased product.
1. Double-click the "Steam" icon on the desktop.
2. Enter your login details and press "Enter" to sign in.
3. Click "Library," and then "Games."
4. Click "Activate a product on Steam."