Just put the chicken the crockpot, add bbq sauce and cook on high for 4 to 6 hours or on low for 6 to 8 hours. You can use boneless or bone-in pieces. I prefer skinless pieces to reduce the fat, especially since the skin does not get crisp. If cooked long enough, the meat will fall off the bone and shred easily for sandwiches.
Sometimes, if there is a lot of liquid, I drain and discard it. Then I shred the meat and add bbq sauce to it.