Motion drive belt on craftsman riding mower

Question

I have replaced the v belt on my riding mower. It worked fine until it jumped the track along the transaxle pulley. The old belt is chewed up in the same location as the new one. If I could tighten the belt once it is installed that probably would take care of this problem. I do not know where you adjust the tension on the belt once you put it on. Please tell me how to adjust the tension on the v belt. PS It is not in the manual.