What about this part?
Adding non-Steam games to the My Games list
Question
How do I add non-Steam games to Steam's My games list?
Answer
Important:
This will simply add a shortcut to your game. This will not allow you to download updates for your game through Steam nor allow you to use this game as proof of ownership for your Steam account. Only games purchased or registered through Steam can receive automatic updates and function as proof of ownership for a Steam account.
Adding a shortcut to a non-Steam game
1. Launch Steam.
2. Go to Games > Add a non-Steam game to My games list....
3. Browse to the directory holding the game you wish to add to My games.
4. Select the executable for your game and select Open