2 things we need to know, your Hboot version and your software version. You can find Hboot by shutting your phone off, then while holding the volume down button press the power button. This will enter the bootloader on up in the heading you will see Hboot version. This is an important number because it will tell us which method to use to root. Also, you can find software version by hitting menu/settings/about phone/software info then find software version, it will either start with 3.29.651 or 3.30.651. Now the good news for you is that someone posted earlier today that unrevoked now works with all versions of the Evo you can find that at
unrevoked. Make sure you read all their instructions through before you proceed. This is the easiest root method. Also, there is another one click method on xda located here:
[ROOT] ~~~ HTC EVO - Universal Auto Root ~~~ (updated for 2.02)(12/12/10) - xda-developers that is suppose to work with all versions of the Evo. Good luck and happy times with your evo.