First of all you need to make sure you have all the right things. I am not making any assumptions here, but this is what you have to have:
- An Intel Mac with at least a gig of RAM (2 Gbs or more recommended)
- Parallels, either downloaded or on a CD
- A Full retail version of Windows, XP is recommended but Win 2K, Vista or Win 98 will all work fine too
- At least 8 GBs of Hdd space (15 Gbs for Vista)
First of all install Parallels. The install instructions come with the application or are easily found on the site. I don't mean this to sound mean, but if you don't know how to install an app on a Mac, this might not be for you anyway.
Once Parallels is installed, launch it and follow the wizard for installing Windows. Most of the default settings should suit you fine. Make sure the DVD/CD drive is correctly set up to see the actual Mac drive (this is one of the set up options).
Insert your Windows DVD/CD at the appropriate time and let it install. Takes about 20 mins for XP or 45 mins for Vista I think, depending on your machine's speed.
*Tip - If you're installing Vista or XP SP2/3 then you don't need to change the VM settings. If you're installing Win2K or XP Sp1 or original, you need to set the VM Acceleration to medium until after downloading and installing SP2.
After you have installed Windows, you should launch it and install the Parallel tools, and then you can go ahead and install Windows programs as you wish.