I’ve only been training for about a year, but I can give you some pointers. First, don’t worry about cutting carbs if you want to gain mass. I have found that intensity and overall performance in the gym is enhanced when you are not carb-deprived (at least 30-35% of your calories should come from carbs mainly early in the day). Second, follow a split program. I prefer making my own programs, but you should focus on a body part (I believe legs should be first as most beginners forget about them) for a few weeks and train that 2-3 times per week, and then switch to a different muscle group for a few weeks.
Something like this worked for me:
Do 2-3 exercises per body part depending on the size of the muscle group. Keep the sets/reps at around 3-5 sets of 5-12. Add in abs, forearms 2-3x per week. Keep your workouts below 90 minutes, preferably more like 45-60. Another very important aspect of gaining mass is para-workout nutrition. I don’t know if you are able to purchase supplements, but if so, look in Christian Thibaudeau’s forum for the protocol. If not, I found eating fruit, drinking water (and creatine if possible) about 30 minutes before workout, and then about 10 minutes before, drinking a protein shake with a lot of my own added sugar/honey to be effective at prepping my body for an intense workout.
During workout drink a diluted protein/water mixture. 60 minutes after, drink a protein shake and 30 minutes after that, a good protein/fat meal such as wild salmon. Make sure to drink a lot of milk/water, and have cottage cheese/greek yogurt and peanut butter before bed. This will provide slow absorbing protein (casein) while you are sleeping.
Good luck on your training. Remember, whatever you do in the gym, make it intense and you will see gains.
P.S. Body fat scales are usually wrong, sometimes off by as much as 10%.