When you want to point out a detail in the drawing or a photo, you can do it with two clicks of the draw tool. After you've finished, make an image of the drawing or the photo with the arrow.
It can look like this.
This is how to make the arrows:
1. Choose draw tool from the shapes menu. Make a line in two clicks. Drag the mouse around after each click to make line curving.
2. In Graphic Inspector click in the colour well and choose colour.
3. Click on line thickness arrows to set the thickness of the line.
4. From endpoints menu choose an arrowhead style.
5. Drag the line’s handles to make it point to the object or detail you want to point out.
6. Drag curving propellers to curve the line.