The key to rooting for the first time, or anytime for that matter, is to read, read, read.. Basically what your going to need to do is, temproot > push the misc.img to exploit your hboot > run the RUU back to froyo (which will downgrade your hboot) > then root using the Froyo method.
First you need to setup sdk and adb. There's other guides but this should help Beginner's Guide to Installing the SDK and Getting Started with ADB - xda-developers
Here's the thread for downgrading Hboot information and downgrading - xda-developers Read through that thread and the links provided in the thread.. Once you have downgraded, you'll use the Froyo method.
This is definitely a long process for rooting but it shouldn't be that difficult. The main thing is to read and follow instructions. Also, if you search through xda general forum you'll find there are a couple scripts for easier temp rooting.
Hope this helped a little and good luck.
Thanks, but that's not helpful. All the temproots I try never give me the Su app.
I've done gingerbreak, z4, and visionary. And I left them all up for about twenty minutes. All I really want is just a temproot, like a tethered jailbreak.
Ok, maybe you did read the first part of my post where is says - Read, Read, Read-
You don't use Gingerbreak, Visionary or Z4... I'll post it agian.. READ THIS THREAD Hboot information and downgrading - xda-developers
It will have links to temp root, which is needed first. Then how to exploit your Hboot, which will allow you to RUU. Then links to root using the Froyo method. This is the only way to achieve root if your running Gingerbread. Basically you have to roll back to Froyo, then root. After you root Froyo you can use any custom Gingerbread ROM you like.
If your only looking to temp root, you have to follow this guide EVO Shift Temp Root for 2.3.3 and HBoot Downgrade - xda-developers