I am so thin. i tried gym and taking whey protein and amino tablets before workout+ amino tablets after workout. is that fine?

Probably fine: Do you think there is a reason for you being "so thin"? Could you have an overactive thyroid? Do you have a healthy gut? Are you absorbing your nutrition? You may be perfectly normal. I have seen many men worry about being "too thin" who put on muscle in their late 20s.

Gaining muscle: You are doing good things. Work out well at the gym. Whey protein is excellent. I recommend you take whey protein before and after your workout. Be sure you have good quality calories also with the protein. Eating egg whites is excellent, also. Yogurt is excellent. Chicken breast is excellent. Get work out advice so that you have excellent exercise routines. Spread your eating over several hours.