Re: How do I look at someone's gallery?

You can access the gallery with your phone (download the gallery app), with this link: http://www.thesims.com/gallery or in game. 
When you want to search for someone you can click the little box next to the search option and choose EA Origin ID.

You can read a bit more on how to access the gallery in game on this link:
http://getsimplyruthless.blogspot.nl/2014/09/tutorial-using-sims-4-gallery.html