How can I use the “Manual Point Alignment” function in Absolute Orientation?

Aligning corresponding points: The grid needs to be in the same viewport as the photo image. Use the ALT key to zoom in on a local area. Select corresponding points with the left mouse button. Press the space bar to switch between the grid and the photo. When there are at least 6 pairs of corresponding points, click {Align} – corresponding points alignment.

How can I use the "Manual Point Alignment" function in Absolute Orientationb