DrupalThemesOnly

The .info file is exactly what it says, its information about your theme. It contains stuff like the name, what version it is. What version of drupal it will work with.

In the .info file you can add regions, regions are the areas like left and right columns, footers headers. If you are familiar with blocks its the areas you add blocks into on your admin blocks page.

Check out the video by tom rogers, it is a great intro to theming and this video is mostly on the .info file.

He has a website at http://www.tom-rogers.com its basically a blog for him.