Welcome to the forums!
How did you end up with S-OFF?
Do you have a custom recovery on the phone? If you have a custom recovery you can simply flash a rooted ROM.
If you don't have a custom recovery, you can put Amon RA on there and then proceed to flash a rooted ROM.
The rooting for dummies guide has LOTS of information and step by step instructions for doing anything. You are already S-off so don't worry about the rooting steps. Read the flashing and switching recovery steps.
http://androidforums.com/evo-4g-all...ooting-dummies-guide-gingerbread-edition.html
Instructions for putting amon Ra on the phone(if you dont have a custom recovery):
you can get the recovery here:
PC36IMG RA 2.3.zip
here are the instructions:
1.download the file.
2.rename the file by erasing the "_RA_2.3" part of the name so that it is only named PC36IMG. make sure not to add ".zip" to the name as windows hides extensions.
3.transfer the file to the root (that means not in any folder) of the sd card.
4.power off (you most likely need to uncheck fastboot. settings/apps/uncheck fastboot.) then press and hold power+vol down.
5.hboot should see the file and select yes to update.
6.select no to reboot because we want to go into recovery and make a nandroid backup.
7.select recovery.
8.select backup and restore and select backup
9. select the first three and wimax. the other partitions do not need to be backed up. always keep one nandroid backup with wimax keys backed up on your computer.
10.now you can reboot.
11.using a file manager of some sort or even through your computer via usb, you should rename or delete the PC36IMG file on your card. otherwise you will be asked to update every time you go to the hboot screen. you do not need that file any more.
Instructions for flashing a ROM:
here is what you do to flash a rom:
1.first you need the vr superwipe:
ZZZVR_SUPERWIPE.zip. download it and put it on your card. (optional)*
2.download the rom of your choice and transfer it to your card.
3.go into recovery
4.make a nandroid backup
5.select wipe from the main menu and wipe dalvik cache, cache, and data
6.select install (or flash depending on which recovery you have) zip from sdcard
7.find the superwipe file and flash it.(optional)
8.find your rom and flash it.
9.reboot.
first boot will take a bit longer then normal, so be patient.