There are a total of 15 dimensions. 7 above and 7 below this earthly plane. Unlike what most perceive them to be like different floors, it is the vibration that differs and not always the physical representation of each realm. The souls that enter the path of evolution do have to work their way up and are under no compulsion to do so. They basically have all the time they need to achieve this. Karma and soul contracts also determine the ascension process.
The 7 levels above us do have physical representations/illusional platforms that separate or provide the entities of higher realms their individual spaces/portals but they at times can be also seen in all levels including the earthly realm.
The lower dimensions are not 'hell' where souls are tortured. The lowest a soul will ever go is the limbo stage an that is when they commit suicide or deny themselves of the light. This is also a dimension called Celeste. Souls are not sent any lower than that. The lower dimensions are for the dark energies to dwell. It's their domain.
I hope this answers your question.
