Are you familiar with ls? That will give a listing of the files, color coded by default.
There is also du -sh which will give you the files and their size.
You can do ls -S which will sort by size. ls -lS will give you the size as well as sorting by size.
There's a bunch of different ways to do it. You could start with something like du -sh |grep G which will only show things that are at least one gig in size, as well as any other files with a capital G in their name.