just installed ubuntu 11.04 and accidentally erased top bar and side bar how do i get them back

I recently upgraded from 10.10 to 11.04 and was trying to install the cube and accidentally erased the side and top bar. The side bar used to pop up when my mouse was on the far left side of the screen and the top bar with the network connections, volume, chat, and power options is completely gone. I was wondering if anyone had any information for me on how I can resolve this. I would also like to get accustomed to 11.04 and was wondering if there are any good sites out there with how to videos or facts on doing so. Thanks, John