Flash Rom and Recover Later I Want to put Android 2.3 on My Phone, its an ZTE Racer with Android 2.1 and the Manufacturer hasnt released the new version i have found a Rom, But im afraid to do it and lose my phone, can anybody tell me how to get my actual version of android back it up so if something goes wrong i can recover later? and how to put the new ROM on the Phone?
You need to install a custom recovery, which can back up your original ROM so you can restore it later.  The Clockworkmod recovery is generally considered the best, there's a build of it with instructions for the ZTE Racer at MoDaCo.