The method is exactly the same for both jala (water) and sthala (air) basti. The only difference is that jala basti is practised in water and sthala basti in air. The full practice is divided into four stages as follows:
Stage 1: initial suction and evacuation
Sit or stand in one of the suggested asanas.
Place your hands near the anus.
Exhale deeply by contracting the abdominal muscles and doing uddiyana bandha.
Hold your breath.
Gently pull the anal sphincters apart.
Do madhyama nauli.
Create a vacuum inside the colon as described under the previous heading.
Suck in water (or air) through the anus.
As you suck in you should carefully manipulate the anal sphincter so that there is free flow.
Suck in as much water (or air) as possible.
Then release the suction and relax; the anal sphincters should be slightly contracted in order to retain the water (or air) inside the bowels.
Breathe out, but maintain the water inside the colon.
Hold the water inside for a short duration while breathing normally.
Then expel the water (or air) and stool into a nearby toilet.
Suck in more water and again evacuate the stool-water mixture.
Repeat the process until most of the stool has been evacuated.
Then proceed to stage 2.