you do not need to root the device to
install custom roms but you need to make sure you have 3 button download and recovery working
(custom roms are rooted for you#)
Turn off phone then press vol up home button then power and when you see logo release this should get you into recovery.
Repeat above with vol down and you should get download mode
If that works then you can look into installing a custom rom. Now if you want to go straight to Gingerbread you will need to install GB bootloaders which makes things slightly more complicated but the guides on XDAdev is where you need to start
---------- Post added at 19:21 ---------- Previous post was at 19:18 ----------
http://www.darkyrom.com/community/in...00m-only.1041/ here is a guide for darkys gingerbread rom. Not my guide so usual disclaimer stands
http://www.darkyrom.com/community/in...-2-first.2382/ another guide possibly simpler.
PLEASE READ THE GUIDE AND UNDERSTAND WHAT YOU ARE DOING FIRST VERY IMPORTANT