How to create a Virtual Try On Lense using the "Image Upload Feature"

Hi, I came across a recent Virtual Try On Dress Lens ( https://t.snapchat.com/VTpLS4mBhttps://www.snapchat.com/add/disguisecostume)

How can I make this feature available at my end? I know how to create the Lens for Fitting the body correctly when the camera is on. But I don't know how to get the feature for a user to Upload an image from their gallery and dress up that image and link it to my e-commerce website. Any help will be highly appreciated.