MizzMisunderstood - You start your exploration of a part of yourself you are not familiar with. You have to understand that as a conscious person you live in a massive place/building that you usually know nothing of. For instance you have forgotten/amnesia your birth and eaerly childhood even though it was very deeply felt and probably left scars on your selfawareness. But also there are other huge areas of you that are unconscious. So in the dream you are moving from the darkness of being unconscious toward a bright light or awareness. See
http://dreamhawk.com/dream-encyclopedia/autonomous-complex/Your dream links with so much that you have not known about I will have to put in many other links to bring you up to date. This is because we have never been told or explained who we are and what we are capable of.
When you touch the light and therefore become more aware of the huge building that you are, you see that you are a dual being - the two flights of stairs. See
http://dreamhawk.com/dream-dictionary/what-we-need-to-remember-about-us-3/#DualBeingThen your inner adventure really begins. You pushed picture of the wall and found a secret/unconscious way. See
http://dreamhawk.com/dream-dictionary/seed/So as this new awareness of your inner world occurs you realise that you are not alone - in fact you have never been alone - for there are guides and subtle influences that have always been to guiding you. But because you have suffered from amnesia due to the culture you grew up in you have not been aware of them. See
http://dreamhawk.com/dream-encyclopedia/archetype-of-the-paradigm/You touch but to not see beyond each door - each door is a different potential you have that you could explore and build into your waking life. To explore it you would need to use
http://dreamhawk.com/dream-encyclopedia/acting-on-your-dream/#BeingPersonThe mirror is a reflection if an aspect of your inner world -
http://dreamhawk.com/inner-life/inner-world/ - and it shows a part of you that you desperately need to contact and release. See
http://dreamhawk.com/inner-life/clicking-on/Then you meet the devil that represent a part of you that was repressed and never expressed because of what happened to you in childhood. Devil in Lived spelled backwards, which is exactly it meaning, because a part of you was never allowed to be released and lived and som became devil - a back to front reflection of you as in the mirror. It spells it out to you clearly - hard to go threw like the reason my mom died when I was 7 and so forth.
Because of that you become aware of a part of you that has felt trapped and has found no way out of that condition. It is part of your Life Work to free it. See
http://dreamhawk.com/approaches-to-being/lifes-little-secrets/It is a lot of reading, but I hope it will make clear the enormous message of your dream and what you can do about it.
Tony