for general practice it is enjoined to: visualize it moving from 1-7 and back down throughout the meditation. This is done for a time of purificaton of the serpent power and the sefech ba Ra (subtle Energy consciousness centers) -this is accompanied with rhythmic breathing and chant.
Then at some time when certain physical and mental as well as unconscious purities are achieved, in the future the practice when the practice becomes more advanced certain practices of breath and visualization and specific work at specific centers is enjoined.
Indeed, In the beginning of the practice you are to visualize the circle around you and being closed off from the outside and being all encompassing of what is in, as well as being a sun in the purity of dawn. All your practice occurs within this circle.