First, buy the right stuff. It'll make your life easier. Also, realize that this is for outside windows only. Try it inside and you'll make a big mess.
You'll need an extendable pole with a 16 inch window scrubber to fit. Also a wallpaper tray, some dishwasher rinse agent and dish soap.
Make sure your windows are closed and hose them down to remove loose dirt. This also cleans the frames and screens.
Fill the tray with warm water and add a generous squirt of both rinse agent and soap. wet the scrubber and apply the solution to the windows. Then just hose them off and let them dry.
Hints: Do one window at a time. Don't clean them in direct sunlight. Hose off the solution immediately. If you are a fuss budget, you may want to buy a 16 inch squeegee and squeegee them dry, but that's only if you enjoy making work for yourself.
With practice, you'll be able to clean all your windows pane-lessly!