Review this walkthrough. It has everything you'll need. I'd type it for you but it's way to long.

http://faqs.ign.com//articles/566/566275p1.html

Good Luck

the slide is loaded with coins you can go through it and when you come down just not get the star. instead jump off the side and there should be a coin back there. then just keep working your way back up the montain. also if your a few short and you missed some on the slide then im pretty sure you can go down it again but if the 100 coin star appears in the middle of the slide your screwed