Broken windows are so common every homeowner should know how to fix them and, in fact, keep basic glazing supplies including a sheet of glass handy for when some other activity comes to a shattering conclusion. You'll need a can of glazing compound (putty), some glazier's points and a glass cutter - all available at a hardware store.
After removing broken glass, scrape all the old putty off the window frame and remove the old glazier's points with pliers. Now measure the opening in the sash - twice, to make sure you get it right. Then cut the glass 1/8-inch shorter and narrower than the opeing, to give it room to expand and contract with changes in temperature.
Next roll out thin ropes of putty between your palms and press them into the sash with your fingers. Neatness doesn't count here - just make sure you've got a continous bed of putty all around the sash.
Press the pane of glass into this bed, ignoring the excess putty that will ooze out. With the glass firmly bedded, take your glazier's points and drive in two long each edge of a small pane, or space the points eight inches apart on a large pane.
Roll out more ropes of putty and press them along the edges of the new pane. Smoothe them out with a stiff putty knife to form a bevel. If there are other panes in the window, try to match their bevel. Don't move the knife too fast: If the compound is stiff it will resist, stick to the knife and form a rough finish.
If you're doing it right, a slight excess will ooze out around the knife on both sides; peel or scrape it off and put it back in the can.
Painting is the last step. Some brands of putty are ready to paint right away; others require a wait. Read the label before you reach for the paint.