Hello Sir, I Am Indian 16years Old In 11th Class.

Hello sir,
I am indian 16years old in 11th class. My weight is just 44.6kg i want to gain weight. My daily routine is
7Am - woke up, A glass of milk and few dry fruits , and a egg
11Am - lunch in school, usually 3 chapati with pickle
3:30Pm - At home, 4 chapatis with pulses
6Pm - At home, Snacks or 1 chapati with picle
7:30Pm - At home, Rice with pulses
11:50 - i go to sleep
I eat chicken once a week
I eat only 1-2 vegetables

Please suggest what to do?
I am thinking for joining gym & for using Endura Mass weight gainer.
Should i do it?
I want to join indian army. And i am underweight. Please help