first off search rom manager it shoud say root users only at the top ignore that for now after you download it you have to istall the clockwork mod after that you mount your sd card down load a rom i am currently using fresh 2.0d
http://www.htc-hero.com/updates-and-cupcakes/fresh-2-0-rom-root-users-only/ now that you did that turn off your phone completely do a wipe and factory reset keep in mind you will lose all the data on your internal phone not your sd then after that go to flash image from sd card and select your fresh 2.0d make sure your rom is not unziped when your are in recovery mode keepin mind that you scroll with the trackball and select by pressing the track ball and when you boot up and if you just get the green htc screen and nothing else after like 5 or 10 mins pull the battery and then reboot into recovery and try another rom i recomend to keep fresh 2.0d on your sd card just incase your other rom does not work
