While, I also found a step-by-step tutorial with pictures and example code which is much better for you to follow, here are the links:
P.S. I highly recommend you to use ActionBarSherlock instead of Google's ActionBar. (Even Googlers suggest as well). It's much easier than above one and fix for most Android versions.
You can download it here: http://actionbarsherlock.com. And these two tutorials are pretty useful:
1. how to use it in Eclipse: http://www.youtube.com/watch?v=FKd1yVpIXHo
2. how to use it to enable actionbar with tabs: http://www.androidbegin.com/tutorial/android-actionbarsherlock-viewpager-tabs-tutorial/