I dont know how to invoke a demon can someone help me? Thanks

Ever since I've joined I have been getting some burning sensations in my chest and it normally comes up to my mouth as like thick spit and when I swallow it , most of the time it hurts. Is it just a coincidence or am I being attacked or something I dont really know.

Is it ok to summon a demon to help with a school subject? If so how do they help you? Thanks

Is it possible to try talking to spirits that are around like in a "haunted" area (or graveyard) if it is possible could you please tell me. Thank