SUGAR GLIDER INFO ? ? ?

How do you know when your sugar gliders are mating ? My sugar gliders are a little aggressive towards each other just a little not much my male suggie is always trying to get on the back or hold her down so my female defends her self. is that normal or do they not like each other ? oh and my male suggie has some kind of bald or scar like parts like on his head it's bald and on his chest he got some kind of scar or furr loss ??? (JUST BOUGHT BOTH GLIDERS TOGETHER)