Help & Direction Please…

I have basic knowledge of html and css but not enough, which brings me here.

I am trying to building a website, one which you have a directory of different locations, you can then enter you postcode and the cloest locations withing the directory will come up (possibly with google map location). Before I start heading down the wrong path, does anyone have any pointers on how and where to start building this directory? is it best treating them as listings???

Help..

Thanks,
Dan