Trying to sell my home...?

this is my 1st house and 1st sell, but someone told me you can advertise your home and you dont need a realtor, just a buyer and then a closing company, they say this will save me the money the relator would have gotten, but again this is my 1st rodeo, i am trying to sell a huge 4 plex in a busy tourist town, and everyone thinks the realtors are shiesty out here, does anyone know where to locate investors or where to place an ad, besides the local paper? what is the basic percentage a realtor gets for commission on a house being sold anyhow?