how to change quantities for different attributes?

First off hello, I am new to this forum and to Zencart. I have a website where I sell t-shirts and they have different categories such as sizes- s, m, l, xl, xxl, and colors like blue, green, purple, etc. I was wondering how I can make it so that there is a different quantity for each size and each color. For example If I have 3 small purple shirts and only 1 large purple, how do I show the buyer the different quantities and make sure they don't buy more than what I have. Right now I have a type of t-shirt with 2 different attributes how do I list different quantities for the different attributes( colors, sizes, etc.). Thank you for your help.

there is a addon stock by attributes. try that...

I'm sorry, where is this located?

In the Free Software Add Ons area (link above). If I read your post right, though, it won't do what you want, I don't think.

In your example the product would have to be a purple shirt, with the sizes as attributes. Zencart can't have attributes that depend on the selection of another attribute.

Okay well if I could at least do it for the different sizes that would work. I downloaded the addon but I can not for the life of me figure out how to install it. I have been reading and attempting to do it for the past hour with no luck. Any help would be much appreciated.