Normally, when you bought an Amiga, it came with the workbench disks, so you were provided with the means of partitioning and setting up the harddrive rather easily, or even running it off of disks alone if you didn't have a harddrive.
I think you mentioned that you're having problems with your HD? How big is it anyway? Until you install 3.9 on it, you can't use drives bigger than 4 gigabytes.