This question always comes up, and it deserves a precise answer. Export the screen as an image from Figma, Sketch or Penpot, then attach it to the request with the paperclip, by drag and drop, or by pasting. Up to six files of 15 MB each fit in one request.
What the AI rebuilds. The structure of the screen: the zones, the order of the blocks and the columns. The text hierarchy, from heading to subheading, label and data. Common interface elements: cards, fields, buttons, lists, tabs. The result is a clickable screen, not one more picture.
What is better written down. The hex codes of your colors and the names of your fonts: written in the request, they are applied as is, whereas an image only gives an approximation. A corner radius in pixels is brought to the nearest of the five levels the engine offers. The states nobody drew, such as an empty list, loading or an error. And the rules of the flow, which live in your notes, never in the image.
What the image does not carry. Component variants, auto-layout constraints and prototype links stay in your design tool. The AI works from what is visible on screen. That is a real limit, but it has an upside: any design tool will do.