A seance is channeling and communicating with spirits. Something most famously known in the 19th century. People still do this either for: 'games'/halloween parties/sleepovers, paranormal investigation, communicating with a loved one which has past away. Some ways people do this most famously are: inviting many friends to gather around and sit on a table while a medium or someone with psychic abilities leads the seance and tries to communicating with the spirit. The most known and risky way is the ouija board. And there is the glass one where you put your fingers on a glass cup and ask the spirit to move it in a certain direction for yes and no. There are more ways but these are the most known ones. I suggest you find articles about it on the internet. WikiHow is a good example.
http://www.wikihow.com/Perform-a-S%C3%A9ance

I don't mess with the paranormal anymore I was skeptic about ghost so I played the Ouija board. after that I now sleep with a light on since then and there have been multiple bad occasions from messing with the dead. I believe the dead should stay dead they do not need any stimulation they have had there time let them be.

I think it's safe. And that's what happens when you're skeptical about everything. I assume you asked it for questions like: If you're really here can you move something and proof it? That's pathetic. But you should have protection and knowledge before performing a seance!

I took part in a seance once in a castle crypt. The woman leading the seance was hit in the face by a spirit. For me the creepiest thing was one of the women taking part was missing two fingers, the middle two so it looked like she was constantly doing that devil hand sign...

Oh that's just damn...