Do you have to put the black ball in the sides in pool?

In pool, the rules for the black ball, or eight ball, depend on the specific game being played. In standard eight-ball, the objective is to pocket the eight ball after all of your designated balls (stripes or solids) have been cleared. You must call the shot and legally pocket the eight ball into a designated pocket; otherwise, you lose the game. So, yes, you do have to pocket the eight ball, but it must be done according to the rules.