Are you talking about the panel that by default sits at the bottom of the screen? If you deleted it, you have by and large two options. One is to delete certain preferences files in your home directory with the effect that default values will be used again.
The second option is to create and design your own panel. Just right-click on the desktop and select Add panel; the added panel should appear in one of the corners. Now right-click on that, select panel options > panel settings and you can modifiy the thing. Set on what screen-edge it should be, set width/height, behaviour and of course place widgets on it. It should be fairly self-explanatory. Popular choices for widgets appear to be Kickoff, Task Manager, System Tray, Digital clock etc; but in the end, I guess, you get to decide.