Wow. It is elemental my friends. Use any 'free' application you can find to crop your favorite segment of a song, etc. to create your ringtone on your PC. You WILL need the Moto Drivers
installed on your PC FIRST. Once you have the drivers installed, then plug your droid into your PC via the USB connection. Wait until your PC is done installing your driver set. Then when done, in the 'Notification' bar on your droid, drag it down and 'mount' your card. Then create in the root of your storage card, a 'media' folder with subfolders of 'notifications', 'ringtones', and 'alarms'.
Then transfer all of your custom ringtones into the ringtones folder and you're good to go. The 'notifications' folder is used when you want custom sounds for incoming texts and emails. The 'alarms' folder is used for your alarm clock should you choose to use it. I personally put all my custom stuff in both 'ringtones' and 'notifications', just for kicks. YMMV.