If you post a code snippet, ALWAYS USE CODE TAGS:
How to use code tags: Using code tags properly
Definitely start with some tutorials on collisions and/or collections. There’s plenty!
Remember: code is only a tiny part of the problem. The much bigger part is setting up the scene properly.
How to report your problem productively in the Unity3D forums:
http://plbm.com/?p=220
How to understand errors in general: