Lie on your back in a comfortable position with your knees bent as shown. Squeeze your buttocks and hold for the duration indicated by your clinician. This completes one repetition.
Repeat for the number of sets and reps indicated by your clinician.
You can place one hand under your lumber spine and use this as feedback to ensure you are not arching or rounding your lower back as you complete this exercise.
Practice makes perfect but little and often is best whilst you are getting the hang of this one.