The first asana of the third series is called vasisthasana. Stretch the arm that is on the hips to the side and move mentally the body to the side till the hand is on the floor and here we go, it's almost the same pose. I tried it and I fell over. I couldn't balance. Why? Because the leg is supposed to be straight above the body. I don't know how I can exercise this.
An idea can be to lean against a wall with the back. M asked some yogis to do this to improve the pose.
This pose repeats during the primary series. Then I lie on the back and do the same. The hip of the leg that is stretched shall remain on the floor.
Usually I add hanumanasana (forward split) here. Perhaps exercising side split is a good idea, too.
I know now what my next steps are.
I've so much to learn, my interest on third series is on ice. It will return. When, stands in the stars and this is good. I'm absolutely happy with first and primary.