I am selling T-Shirts within virtuemart and I want to have pictures link to different sizes of the shirts. So if you click on the picture that says "small", it would add the size small to the cart.
I wasn't sure on what to search for for this.
It depends on whether u require stock control or not.
With stock start with child products and multi variants
https://docs.virtuemart.net/tutorials/product-creation/221-multivariant.html
If not you can use simple custom fields ...
https://www.gjcwebdesign.com/joomla-virtuemart-tips/793-virtuemart-3-add-a-simple-cart-select-variant-by-custom-fields.html
If want images to click on there are some plugins available but sizes don't normally look different