I did not write these instructions but they are very good instructions.
1.) To install a new ROM you first have to download the said ROM and put it on your phone's sdcard. (Obviously.) Second of all, you have to find the kernel you want to use. Most ROMs come with kernels but you can still download the kernel of your choice.
2.) Once you have the ROM and kernel of your choice, go into recovery mode by powering off your phone, turn it ON WHILE HOLDING the VOLUME DOWN button, do not let go of the volume down button until you're at the boot screen. Select "Recovery" by pressing the VOLUME DOWN button and selecting it by pressing POWER.
3.) You're now in recovery mode. Make a NANDROID backup (varies on how to do it depending on which recovery you're using) if you're on Clockword Recovery scroll down until you see something saying "nandroid" when there select it with POWER, then select the option that says "Backup". (Not sure how AmonRAs recovery works exactly.)
4.) Wipe data/factory reset twice, wipe CACHE twice, wipe Dalvik-cache twice. (Dalvik-cache is located in "advanced" in the main recovery screen.)
5.) Choose "install zip from sd card" then "choose zip from sd card", press up once and it'll bring you to the bottom of the list and you should see your ROM, select it, then install it. Once done installing, go back and reboot your phone, it should be all done now. IF, IF, IF, you have another kernel, after installing your ROM, re-wipe CACHE and DALVIK-CACHE, THEN install the kernel.
