I'm getting this error: the modifier public is not valid for this item

[Kurt-Dekker]

If you post a code snippet, ALWAYS USE CODE TAGS:

How to use code tags: Using code tags properly

How to understand compiler and other errors and even fix them yourself:

Assets\MouseLook.cs(29,62): error CS1003: Syntax error, ',' expected

Errors are there to help you. It’s a good idea to try and learn how to understand them. Try to apply the breakdown in this post of your original error to the new error you’re receiving. If you don’t understand a word, don’t just gloss over it. Ask what the word means here, or research it elsewhere. Cultivating a habit of research will pay dividends for you in every part of your coding journey. Here’s a breakdown of your specific error, but try applying this process to any other error you may en…

Beyond that, here is how to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220