How to create an action when radio button is selected?

[UN17]

I am building a web store and want to know how to make an action happen when a radio button is selected. This web store has multiple configuration options, so I would like to know how to do something similar to the Originpc style of configuration, found here:

http://www.originpc.com/configurator/d/d4.aspx?SYSTEMID=7

I primarily want to know two things. First, how does, when one object is selected which is greater in price compared to the first object, the gray portion at the end indicating the difference in price changes. I would like to know how to do this.

Second, the subtotal in the right sidebar increases and decreases depending on the configuration of selected items. I would like to know how to do this also.

Thanks for your help

 

[chrishirst]

use the onclick event of the input element to call a function.

the gray portion at the end indicating the difference in price changes. I would like to know how to do this.

Change the width property of the element to suit the value selected.