Hate to say it but it's a fairly simple process, what you need to do is calm down and prepare to read a lot of information and watch some youtube video's so that your comfortable with the process before you actually try to do it, I bet I spent almost two weeks reading and watching youtube video's before I actually rooted my phone and that was a year ago. Sprint is going to know your rooted, I have called them before about issues and they have looked in their system and said it might be the "blank" rom that your running, but they are not going to seek you out as soon as you root the phone, but when you get into Tech support issues or needing to take your phone into a repair center is where you could run into issues.
This link is about rooting the Evo:
http://forum.ppcgeeks.com/htc-evo-4g...roms-wipe.html
Also get on yourtube and watch some video's of people rooting their phones and before you know it you'll be rooting your's, good luck!