I always recommend beginners do a full body routine. As well, you should focus on very compound exercises. I have a standard beginner routine which I recommend to lifting newbies. It is to be done 3 days per week or every other day. Make sure to tweak the program according to your best and worst body parts. Change up the rep ranges, tempo, exercises, and training methods frequently. Also, make sure you do your diet right. Diet is more important than training methods when it comes to gaining muscle mass. Here ya go:
Full Squats 3 x 8-12
Romanian Deadlifts 3 x 8-12
Deadlifts 3 x 8-12
Wide Chinups 3 x 8-12 (Or as many as you can do)
Bench Press 3 x 8-12
Military Press 3 x 8-12
Bicycle Crunches 3 x Near Failure
Reverse Crunches 3 x Near Failure
Another good idea is to make another list or two that matches this one and rotate between them each training session.