Jos'er here. my best advice would be look for the evidence yourself. spiritual satanism is a very very personal thing and most proof or evidence will come out of your personal meditations and studies. i would advise to start doing some energy work like breathing exercises or opening the chakras. then when you feel a bit of energy you can start TRYING to communicate with demons and Satan himself. i will say, to properly hear or see these demons you have to be very open psychically otherwise they will come and you will not know.
personally i wouldn't advise a non-satanist to try to communicate with demons but if you really are honest and have genuine, TRUE intentions towards Satan and satanism, i would light a candle, get comfortable and relax, focus on the candle and ask Satan "is Satanism for me" or something along the lines of this and try to have a conversation with him while remaining completely open and relaxed.
Hope you still lurk around OP, I know it's been a month before you got a reply. best regards!!
Breathing Exercises or Pranayama: http://www.angelfire.com/empire/serpentis666/Yogic_Breathing.html
Opening Chakras: remember to go by order! http://www.angelfire.com/empire/serpentis666/OpeningChakras.html