Arduino parking radar - some advice please.

Hello guys ! I have searching over the internet to find an parking radar to interfacace with an PC . I want to build an parking sensor for my car .
I have an old EEEPC 701 with 3 USB ports and I will use them to do an carputer with some functions . One of them will be an parking sensor , an gps software .
How I`m saying , i did not find an starting point to make an parkin radar . Can someone from here to help with some starting points ?

Thanks in advance.

Start here:
http://www.apogeekits.com/ultrasonic_parking_sensor.htm
or here

(lots of other articles in playground)