Using PVC solvent cement:
Place glue inside collar of bend and over end of pipe to go in this collar. Push and twist together in one motion. Positioning as required. When roughing in waste pipes and bends it is a trick of the trade to mark how far into the collar the pipe is and to also mark the required angle across the top of the pipe and the bend with one straight line pencil mark. This makes it easy to simply line up these marks again once glue is placed.