Add A Text Input To Selected Options?

I'm trying to make a template generator. I want the visitor to select a background (options: none, color, image). If 'color' or 'image' are selected, I need the appropriate text input field to be displayed.

I've found code to do this which I was able to understand and install. I've also found code that was well beyond my current understanding and that I couldn't get to work to save my life.

The problem is that the code snipped I found and installed is designed to work with a single dropdown, and it's beyond me to figure out how to turn it into a function that could be applied on the page multiple times. I have no idea if it is possible with this piece of script, but that is what I need to have whatever script I use do on the page.

This is the snippet I installed:

Code:

function Choose(op) {
document.getElementById('None').style.display='none';
document.getElementById('Color').style.display='none';
document.getElementById('Image').style.display='none';

[Code]....