PC on an imac

[bill bigrig <billbigrig@yahoo.com>]

Howdy,

 I bought an Imac a year or so ago, 550 G disc, 4G ram. It says it has 
parralels or somethignto that effect. I've only used the thing for 5 or 6 
hours, toying with garage band. Do I just go in and click on something to 
bring up the PC part? I'm assuming it came already in the computer. Any 
advise on this would be greatly appreciated, such as how to switch between 
the 2, how to work a plug in for windows while simultaneously running mac 
plug-ins, etc.
Rig