Actually the full step is this but i stuck at step 5
Make sure you have the usb driver installed from the android sdk
1. Turn your desire off
2. Hold the back button and turn your desire on
3. When you are at the white screen, make sure BOOTLOADER is selected and press the power button
4. Wait a few seconds then press volume down to select RECOVERY and press the power button again
5. When you are at the screen with the red triangle and the phone, plug in the usb cable
6. Run the recovery-windows.bat script from modaco r5 root pack
7. When the recovery menu appears select 'Flash zip from sdcard'
8. Select the radio zip file and press the trackerball to confirm
9. Press the trackerball over 'Reboot system now'
10. When the radio image has finished being written unplug the usb cable
11. The phone will reboot a couple of times and then return to a normal state with your new radio
by the way i just install the rom witout the radio is it ok?
and the radio here means the radio on the phone right?
Don't really get what your issue is (i.e., what are you stuck at?), you don't know how to install the android SDK USB driver? I did it by following this page:
This is one of the steps using the unrevoked method, but I don't know if it's applicable to your modaco r5 method (I guess it should)
the FM Radio you're thinking, it will have impact on stuffs like your reception and using the 720p camcoder, so it's recommended to flash.