How to use Mac OS X Lion and Snow Leopard on same partition?

[The Picture]

In the old days to partition a hard drive on a computer the hard drive had to be erased/ reformatted first. Do I appreciate properly that partioning a hard drive no longer requires this? Can somebody give details, as if I'm 6 years old, how to do this? I desire to upgrade to lion so I am able to make use of i-cloud on a mpb nevertheless must still have snow leopard due to a couple of ppc programs/files I still need (such as the data in chronos personal organizer, quicken 2007, and perhaps a hardly any more). So how precisely do I do this, with no reformatting etc.

[Jezriah]

In the old days to partition a hard drive on a computer the hard drive had to be erased/ reformatted first. Do I appreciate properly that partioning a hard drive no longer requires this? Can somebody give details, as if I'm 6 years old, how to do this? I desire to upgrade to lion so I am able to make use of i-cloud on a mpb nevertheless must still have snow leopard due to a couple of ppc programs/files I still need (such as the data in chronos personal organizer, quicken 2007, and perhaps a hardly any more). So how precisely do I do this, with no reformatting etc.

Launch Disk Utility->Help->Disk Utility Help->creating new-fangled partitions on a disk. Make a note of, that to vigorously put in a partition; journaling has to be enabled on all partitions. I have my iMac's 1 TB HD partitioned into three bootable volumes.