In Pictures: How to Clean and Retouch Old Photos w...
6. Begin by selecting your background layer in the layer palette. Locate an area of similar pixels to the affected area (usually close by) and click them while holding down the <b>Shift</b> key. You have just defined the source pixels we’re going to clone in order to cover up wear and tear.
In Pictures: How to Clean and Retouch Old Photos with Paint Shop Pro