!!HELP!! Ultrasonics --Not Maxbotics Sensors--

I want to add ultrasonic transducers to my arduino to create a obstacle detector for my (what else but my) Autonomous Robot. I do not have, nor do I plan to own the Maxbotics sensors available online that I keep finding information about. My question is if anyone knows how to use regular ultrasonic transducers to create a range finder.

Help Me please....Does no one know how to do this? I keep trying to figure it out and its not working. :'(

HELP!

I didn't dig too much. Try this: http://www.adrirobot.it/sonar/sonar.htm