how to download photo booth for mac

Photo Booth is installed as part of the Mac OS and its related software. If it is not in your Dock, double-click your hard drive icon and open the folder "Applications." Photo Booth should appear there. You can click-drag its icon to the Dock if you prefer to have it quickly available.

Lacking any further information about your Mac and what OS version it it running, that's about all I can offer.