You can store your downloads in your account when you signup!
Place your start-up product screenshot on this outside environment. The Nexus 7 mockup stage is being held up by two hands at a flat, frontal view. The background suggests a city street at dawn or dusk. This extra wide image has a blue haze with headlights shining through. The stage itself is at portrait orientation and is 800 x 1280 px. It has the feeling of walking to work or waiting for a bus early in the morning or coming home just before dinner time in the evening.
Drag & drop not supported, but you can still upload via this input field: