Hi Val, Repairing plaster is not the same as fixing drywall. First off, be aware that even though you fix these cracks, it is likely either they will reappear or others will show up, as old plaster is brittle and cracks due to house settling and moisture/temperature changes. Cracks are more noticeable in winter, as humidity levels drop and moisture is sucked out of the walls. To repair them, use a pointed scraper, such as a "5-in-1" tool, and gouge out the crack on either side to produce a V-shaped groove, basically to allow enough patching compound to get into the crack. Blow away any dust. Using plaster of paris, NOT drywall joint compound, mix a small amount and fill the crack with a putty knife. Only mix as much as you can use in about 10 minutes, as it sets hard very quickly. Smooth the area with the putty knife and after it begins to set up, but before it's completely hard, lightly wipe the area with a dampened sponge to blend the patch in with the surrounding wall. If the cracking is severe, we have always opted to place new drywall over the walls, resulting in a new appearance. By screwing 1/4" or 3/8" drywall directly over the plaster and finishing like tradtional drywall, you will be spared the inevitable plaster cracking that unfortunately plagues older homes. Best of Luck.