It only pulls up folders relating to Steam

Do you mean uploading something on steam?

I have the Steam version and when I try to pick a file it pulls up stuff about Steam

Hmm, this happened for me once, I tried a few days later and it brung up the other folders and stuff, but, I expect other people will have a solution.

Eh, to upload a texture you have to buy an item that allows doing that and then upload the image using this page or by clicking "Edit" button near that item in your inventory. It doesn't really matter what version you're using, Steam or standalone.