This support article applies to a previous version of Layer. If you're using the newest version of Layer, some features and navigation described here may look different.
The Marquee Tool lets you draw a rectangular selection on your canvas to define the area you want to regenerate or edit using AI. Select the Marquee Tool from the toolbar, draw your selection, choose a style, enter a prompt, and click Forge in Selected Area. Accept the result to apply it to the same layer, or add it to a new layer to preserve the original.