Rooting -- the easy way -- http://unrevoked.com/m. This will give you an app that grants you root privileges in Froyo (2.2).

This is the easy way to "try before you buy" rooting, since a permanent rooting solution requires you to flash a new operating system (ROM) onto the device.

If you want a more permanent solution see http://androidforums.com/evo-4g-all-thin...

In fact, read the idiot guide and get to step 13.