Please note: This phone has not been released, and therefore the following may or may not work:

First, we'll discuss USB tethering.

USB tethering can be done without rooting your phone. You can use an application called PDANet. You can find that in the Market. After you install it on your phone, you also need to install it on the computer. To do this, click on the following link:
Download PdaNet

After you're done downloading that and downloading the PDANet application from the Market, open the application. Click on "Enable USB Tether". After that, plug your phone into the computer. You should see a pop-up on the right hand corner of your screen. You can click on that to connect. If you don't see that, look for the PDANet icon, and right click. Then click on "Connect Internet".

There you go! You're now tethering via USB!

WiFi Tethering: Coming Soon!