Okay, so after you have rooted your Sprint HTC Hero and have your ClockworkMod Recovery flashed via RegawMod, you can boot into recovery and do what is called a Nandroid backup. A Nandroid backup is basically like a snapshot of your current ROM and setup that you can restore back to if you ever need to. You can do multiple Nandroid backups if you want. For example, if you flashed a new ROM and set it up and then wanted to go back to your stock ROM, you would make a Nandroid of your current ROM first so that you can restore to it after you are done with your stock ROM.
You boot into recovery by powering off your handset and then pressing and holding the volume down button and hitting the power button for about two seconds and then choosing recovery. Choose Backup and Restore to do a Nandroid.