A good way to understanding patterns is to take apart some old clothes. T-shirts, skirts, pants, etc. Cut them at the seams. Notice the shapes and how they are put together. Or you can go to a craft/fabric store and buy ready-to-use patterns too.
I think reconstructing clothes is a good way to get started with sewing, especially if you aspire to create your own clothes from scratch one day.

You can check out this thread for some ideas:
http://forum.asiajam.com/made-me/203...ucting-ts.html
Good luck!