hey there jimma!
I just ran into your thread and noticed that we are on the same boat! well sorta. I to find it hard to train properly while having school, work, and rugby into my life. But i find it easy to gain weight and im on a cutting diet.

I understand you are looking to gain some LBM and grow some size. You chose the right place to ask cause the people on this forum are great!
as for lifting... I suggest you lift heavy, say 4-8 reps of your max and just make sure your eating the "right" foods. Stay away from
fast foods and candies cause they go straight to fat. Make sure you get your protein in, but make sure your getting carbs in as well. Carbs = energy so dont think you will get fat by eating so.
to be honest, i think 10 kg of LBM is kinda pushing it for one year and its more important to have
proper form than to hit your rep range. Make sure your squeezing at the peak of your reps and hold for about 2 seconds. 4 reps of proper form are better than 10 reps without proper form.
just keep at it and make sure you educate yourself on this forum! you will make gains much easier that way, just one thing...
what position do you play and do you play for a league?