Hi guys

I'm in real trouble. I was having problems with my mac not responding well. Everything began whenI bought Leppard and installed it. I had my Administrator Password and everything was perfect. After I installed Leppard everything changed. I messed up my passwords and my computer started to act weird. I also bought a new copy of Windows XP and installed it over Paralells Desktop (I like windows since I use it for my PDA's). Then, to make a long story short now my computer does not start up since does not recognize the Disk where Leppard is installed (when I saw my mac acting weird I backed up all my files to an external hard drive). I also tried to install Leppard from scratch but when I open the instaler and go to Disk Utility my mac does not recognize the disk, it only sees the CD room where Leppard not letting me install it. I was surfing the web and reading and I could find out that I can format the hard drive and even create a new disk partition where to install Leppard. I have everything (softwarewise). I have leppard, iLive, etc. I only lack of knowledge to format the hard drive and create a new disk where to install the Leppard OS. I know that the most of you would say take it to the Mac Genius at the apple store for repair but I will like to try myself first and if does not work then I would use my warranty. Please anybody tell me how to play with the Terminal in order to install Leppard in a new Disk. Any help will be greatly appreciated