I just started lifting at the beginning of June.
My routine now is doing a total body lifting workout (not targeting one specific muscle group) three times a week and running & doing abs in between each day of lifting. I have one rest day where I don't exercise.
Obviously I'm not a huge expert on the subject matter, but if you're looking to gain muscle mass, it's all about eating. In order to grow bigger, your muscles need more nourishment, so naturally, you have to eat more calories. That's why bodybuilders alternate stages of bulking and cutting; bulking, they eat above their baseline caloric intake to gain muscle. When cutting, they eat below that caloric intake to lose fat.