How would you winterize this sprinkler system?
The hardware you will want is a valve like the one on your car only shorter. Rainbird and Orbit both used to sell them. Using drill a 32nd smaller than the valve you will need to install.  Punch a hole into the 5 station manifold shown. Screw and glue the valve and then get the compressor . Hook the air hose to the valve with one of the 5 water valves open. Think and remember, one of the 5 water valves open has to be open. Then you can turn on the compressor. Without knowing what you have feeding that manifold, remove the air before you switch water valves.  If you don't, you may find yourself hating life as you dig up your yard to find where the compressor caused the line to fracture.

If your luck is any good and you turn the water back on, you won't find yourself repeating the action of finding the other leak the compressor caused. When your satisfied  the air has cleared most of the water in the line, remove the air. Open the next valve in the line. Now you need to close the valve on the line you just completed. If you are wondering how to open and close those water valves, I'm going to recommend your local Craigs list to find another gardener.