Some help for a noob

So this is my first time playing demon's souls. I would appreciate any advice you guys can give me, no matter how easy or stupid it sounds.

So Im in the nexus. But I cant buy from most of the merchants. I've been able to deposit my items, been able to trade from the old blacksmith, but I cant buy spells from the other merchants. One guy just calls me a brute and the other just nicely desmisses me. Idk what to do.

Im a wanderer btw. Any ideas?

Not every class can use magic. It's been awhile since I've played Demon's Souls, so I don't remember the classes, butI suspect that is the problem.