First make sure you’ve warmed up by doing a few Sun Salutes.  Then do these standing poses: Triangle, Side Angle and Pyramid.  Then come into Wide Legged ForwardFold and lower your head to the floor.

If you cannot get your head to the floor, walk your hands forward as if you are coming into a Wide Legged Down Dog and while keeping your heels on the floor and your legs straight, bend your elbows out to the side and touch your head to the floor.  If you can touch your head down, then walk your hands back a little and try again.  Do this repeatedly over a period of time and you will eventually be able to get your head to the floor with your legs vertical. 

Next, come up into Tripod Headstand.  Initially you will want to be near the wall; just an inch or two away.  Begin to separate your legs wide apart.  Your toes will be facing straight ahead, into the middle of the room.  When you cannot separate your legs any wider, begin to move your buttocks backwards towards the wall behind you as you beg into fold at the hips.  Keep your legs straight.  Draw your quadriceps up towards your belly and move your belly in and back towards your buttocks.  As you fold, turn your toes towards the floor.  Try to control your descent by keeping the buttocks moving backwards slightly and keeping your quadriceps and your core engaged. 

When you can control your descent to the floor and touch your toes lightly down, you are ready to start working on going back up. 

Make sure you do not hold your breath as you are playing with this transition.  That can build up a lot of pressure in your head!