Nayaswami Bhajana has created an online course for deepening the meditation practice in general, but also the Kriya technique, through various Pranayama that prepare the physical body, the astral spine and increase awareness of it in order to practice meditation more deeply.
There are the following videos: a short presentation of the course, 3 lectures and 2 videos with guided practices.
Presentation of the course
First lesson
Second lesson
Third lesson
First guided practice
Second guided practice