Merlin, in simplest terms, partitioning divides a drive into sections. This is normally done when setting up a brand new hard drive, or one that has been completely cleaned off and has no data on it (I do this about every 6 months to keep my 10 year old computer running fine). If you bought your computer with Windows already loaded, you don't need to worry about partitioning, as it was already done for you. Not really something that should be messed with if you don't know what you're doing, because if you delete the wrong partition, or overwrite an existing one, you will lose every bit of data on that drive. Nothing to be gained by doing it once the drive is already in use.
Hope this helps!