You don't really need seperate days for different muscle groups/body parts at your level. Assuming you have access to adequate equipment, here's all you need for legs: squats, Romanian deadlifts, calf raises. Here's all you need for your pushing muscle groups (chest, front of shoulders and triceps): bench press, overhead press, lying triceps extensions. Here's all you need for your pulling muscle groups: chin ups or lat pull downs, rows, dumbbell or barbell curls. Here's all you need for your abs: decline sit ups, woodchoppers.
Do 2 working sets of everything, after properly warming up for each exercise. Do squats first on their own. Once you've done both sets, do the following circuit: bench press, row, calf raise. Rest for 1-2 min after each round of the circuit, but minimise the rest between exercises. Once you've done 2 rounds of the circuit, superset overhead press with lat pull down. After all that's done and dusted, perform 2 rounds of the following circuit: Romanian deadlift, curls, tricep extensions, decline sit ups, woodchops. For every exercise, use weights that you can perform for at least 10 reps, and for the first 2-3 weeks these weights should be so light that after both working sets you should feel like you could easily do another set. Don't train to the point of failure. Occasionally you will fail a rep, and if you do, stop the set immediately. But at your age and level you should be avoiding failure. If you want to hit 10 reps in a set, you should use a weight that you feel confident you could lift for 12-15 reps.
So, the session should look like this:
1. General warm up -- 5min light cardio, dynamic stretching
2. Squats -- a few bodyweight sets, a few light sets, 2 work sets.
3. Bench press/row/calf raise -- 2 light sets and 2 work sets.
4. Overhead press/lat pull down -- 2 work sets (you should be warmed up enough by now, so only do warm up sets if you feel the need for them).
5. RDL/curl/triceps/sit ups/woodchops -- 2 work sets.
Do that whole workout three non-consecutive days per week, and eat a lot. A LOT. Good food, and lots of it. This should take you 40min to an hour. Eat before training, eat after training, drink plenty of water while training, stretch and do some foam rolling if needed. Progress in smaller increments than you think you can handle, and troddle along slowly.
After several months of this, you may need more volume for each muscle group, at which point you may benefit from breaking your program into an upper/lower split, but for now, full body, three times a week, avoid failure, progress slowly, master form on each movement, and eat eat eat.
