Hey Dan. SSBB's single player is hard, we know. You said that you don't know what to do.
May we ask, are you at the part with 4 doors, and a save point (Inside Subspace) were you have an annoying map that doesnt help?
Well on the map, you see all those dots? You have to go to each one, then you unlock these bowser faces and they are boss fights.
If that didnt help, post again
or maybe visit the SSBB website (although it doesnt really help!)
www.SmashBros.com