Ok, so you read the stick as you said here .
What routine are you doing? Try something like Ice Cream Fitness. Decent routine based on Stronglifts/Starting Strength with some accessory work thrown in. Track your weights and try to increase say 5lbs/2.5kg each workout. CONSISTENCY is key - hit the gym three times a week.
Eat properly. As a skelly like me, I know you'll find it tough. Lots of stuff to help you on your way though - drink enough water, stop drinking fizzy drinks/alcohol, etc.
Work out your TDEE and the amount you need to eat to bulk. Varies based on weight, age, height, etc, but at a guess I'd bet you come out at around 3500kcal per day. Use a TDEE calculator and get back to us.
Then finally, consider steroids. Safe, legal, and EXTREMELY effective. Best thing I ever did.
Two years ago I was 50kg and doing Stronglifts. I did get my squat up to 65kg and could deadlift 90/100kg depending on the day, but my eating was appalling. I didn't put on weight, and then my panic attacks/anxiety got so bad I could barely eat.
About a year ago I got over it though and started to eat properly, ish. I only managed around 2500-3000kcal a day, but it was better than the 500 I was managing at times.
Fast forward to now. I'm hitting 3500 easily, and my gym routine is very consistent. Then I started on gear a few weeks ago. We're only on week three, but I'm hitting 4000kcal+. Hit 65kg for the first time in my life yesterday, a 5kg increase in about two weeks. I've never felt better personally.
Just wish I knew all this and did it sooner.