I built a new View that shows all a user's nodes in a list, and I managed to get it to work like this "http://url.com/user/%USERNAME/items". But I'd like to make it "http://url.com/%USERNAME" and then chagne the profile to "http://url.com/%USERNAME/profile"

How would I do that? It seems like it should be something I would be able to configure in Views but the videos I've watched and documentation I've read hasn't really showed me (or I may just be dumb). Can someone please shed some light on this?

Thanks!