Adding Sizes to a product

[mxs]

I have a simple t-shirt product
I have tried to add sizes to the product and have failed completely - probably an oversight on my part.
Can anyone help?

[llegrand]

There is a global option already set for you use and it has sizes and colors,   here is some info:

https://abantecart.atlassian.net/wiki/spaces/AD/pages/29819029/Parent+Child+Options