How do you add stuff to your collection. Sorry am quite new
on the top-right of your screen (if your using a desktop/laptop) you can see 4 options. follow, add, rate and related games. just press the 2nd option "add to collection". It should give you the option to what collection you want to add it, you can make a new one or add to a existing collection that you made before.
After that, go to you're own account menu and you can see "library". click to go to your added games.