Stud wall

Hi all.
I'm looking to build a store room in the corner of my round top shed and will be looking to put a set of stairs up to the roof of it to store bits and peaces. I was wondering what kind of load a stud wall would take if I was to make the store 12x10 and have 2x6 joists stretching from side wall to top of stud wall 10foot length ways. And stud frame is 2x4...