So the focus is on building chest, back and shoulders to round the off. Plus of course eating a little more than you did in the past.
I had different ideas, but in the end, especially for a beginner the best routine is one that you can stick to (and works!)
I'd just focus on a single workout repeated twice a week for both gym days, leave room to go play sports with your friends on weekends and the other days, if you want to move you could do the daily dares, maybe a challenge or nothing at all! If you aren't playing sports on weekends, perform either a random strength workout from here or specifically one for your abs, since I didn't include any specfic exercises for them or, hear me out, instead of that, daily dare or whatever, do the
Core Strength Add-on program! How does that sound?
Now, this is quite subjective and how I would do it in your place and not necessarily what works best for you, but you need to start and gather experience to be able to make better plans.
The focus is on upper body, but it finishes with a leg and a hinge exercise, so these parts are not completely forgotten!
Make sure to push yourself, especially Thursdays, since you have a lot of days to recover! Also make sure to control the negative repetitions, go all the way down, not rush them; that prevents injuries and is better for hypertrophy.
So the routine would be:
(general warmup)
Overhead Presses
warm up set
2 sets
Dips
2 sets
Pull Ups/Lat Pulldowns
2 sets
Dumbbell Rows
2 sets
Dumbbell Front Raises
1 set
Squats (whatever squat variation you prefer, add weight if necessary)
1 set
Stiff Legged Deadlifts (go to single leg to better challenge yourself, then add weight if you need it to progress)
1 set
In terms of weight for the overhead presses, go medium heavy for 6 reps to warm up, then heavy for the first set and if you get less than 10 reps, go lighter for the next set. If you hit 12-20 reps, keep the weight the same for the next set and next time start heavier.
I hope this is a good starting point.