You can store your downloads in your account when you signup!
Relaxing on a couch watching a movie. This woman holds up her iPhone 5s gold, taking a look at your app. She’s lying on a great comfy couch with gorgeous red and white striped cushions. She’s cuddled up to relax for the night with your app. The iPhone 5S will hold a mockup image of 640 by 1136 pixels. This would be great for a leisure app, or some sort of social type app.
Drag & drop not supported, but you can still upload via this input field: