Social Media images are powerful when promoting your designs. It is proven people will take more time to look at a social media image than they will a link to your shirts.
Upload the images in the 'Design Management' page. The page in which the design is titled and mark up applied. This page can be found under the 'Products' tab in the store admin.
To share social medial images click on your design in the store. This will take you to the 'Product' page.
Click on the social media platform you wish to share your social media image. Follow the pop up instuctions.
Here is a picture of a social media image being shared to Facebook: