Help with new super mario bros?

Question

in new super mario bros DS i beat the big bowser and saved the princess but i dont know how to unlock level 4 and 7 and this would be nice... how do u get to those cannons in all the levels PLEASE HELP!

Answer 1

to get to level 4 and 7 u have to beat the castles in worlds 3 and 6 as the little mario.  to be little mario u have to get that little blue mushroom.

Answer 2

http://www.gamefaqs.com/portable/ds/file...

that's a guide that shows all secret exits.

and the video walkthrough for everything is here (and it includes the alternate exits as well:

http://www.youtube.com/view_play_list?p=...