Simple shirt design

Hi,

I'm helping my friend with setting up shirt design for his Woocommerce page, but I feel I'm kinda lost and so I thought I might get some help here.

I have managed to setup the tshirt product with variations, which means I can open the product, select from color and size and add it to cart.

The next step would be to connect it with FPD, so I can add text and/or image. Here I got lost. I see one viable option: add Customize button, that would open the FPD designer with the selected shirt (including color) and allow to add text and/or image. If image and/or text is added, confirm it and it would be nice if this was reflected on the tshirt on the picture.

Could you please point me to some articles or anything that would help me to set this up.

Thanks.