Rooting will not make paid apps turn to free apps. Ignore the virus warning. Using AndoZip from the market, take it out of the download folder and put it on the root of your uSD card (not in a folder, just near the bottom of the list of folders). To move an item just longpress it and select move. Hit the back button and select the move here button.
Tap on item then select install. When done, select done.
Go to menu /settings/applications/development/make sure the USB debugging box is checked. This will help with the install.
Go to app draw and open up app. Select run.
It may take several attempts, if after 12min it doesn't reboot your phone, pull your battery and try again.
On any failed attempt you must reboot the phone,pulling battery and starting over constitutes a reboot.
Once it reboots your phone go to the market and update superuser. Then download a Busybox installer from the market. If it fails the first install, select the alternate install location.
You now need to find a suitable recovery to install so you can make a backup of your system in the recovery (this is called a nandroid). This is important, if you accidentally delete something that borks your system, you can restore your backup and all is good again.