Your Steam ID is needed to request your game list, your profile should also be public - and not private.
Obtaining your Steam ID can be done by going to your profile page in Steam and then right clicking the background. It should then allow you to copy the URL, which you can paste in here. You could also do this on the web version and then copying the URL from the browser bar.
The ID should be 17 digits long, numbers only. Example: 1234578901234567