Javascript and WordPress Query

If you look at this page http://www.autobulbsdirect.co.uk/wiper-blades/ you will see on the right hand side there is a “Find wipers for my vehicle” which is launched by a javascript command.

I am wanting to use the same link on the Shop Now button at http://www.windscreenwipers.org.uk/about-us/test

I’ve tried copying the javascript line from their site and dropping into the a href tag on my image but nothing works when you click on it (bear in mind I know zero about how javascript works!

Can anyone offer a solution so that I can execute the javascript pop up?