Dialog
Choose Placement > Dialog to place a coach mark so it points to an open Photoshop dialog box. The coach mark should describe how the user interacts with the dialog box that popped up. A Dialog coach mark always points to the center of the vertical edge of the dialog box. Generally, put all instructions for a Dialog coach mark in the one coach mark.
Dialog coach marks can’t be played when creating the tutorial. They can only be viewed when you are previewing the tutorial.
Canvas
Choose Placement > Canvas to place a coach mark on the canvas of the open document. You’ll create this coach mark by dragging the Horizontal position and Vertical position sliders to position it. Use the Arrow direction buttons to change the direction of the pointer. Click the double-arrow button to change the location of the pointer on the coach mark.