How can I transfer files from my MacBook Desktop to my IPad2?

Depends on what you mean by, "files".

You can sync data using iCloud > Apple - iCloud - Everything you love, everywhere you go.

Assuming you have an App on your iPad that can handle the files types you wish to transfer:

You can copy files between your computer and apps on your iOS device that work with File Sharing. For example, you can create a document in Pages on your iPad, then copy it to your Mac so that you can open it in Pages for Mac OS X.

About File Sharing on iPhone, iPad, and iPod touch - Apple Support