How to go from being a thin guy to healthy handsome body?

I’m 27m. I belonged to a poor family and now I’m alot better financially.

I also have no meat on elbows neither on knees, it’s only very thin skin on top of bones and sometimes I am able to bend them the wrong way but luckily not break them.

My voice is also thin like kids.

I also have gotten some digestion issues but they are going away with exercises (Which I only did for the first time a month ago) and syrup called Gaviscon. I’m eating peanuts all day long now, a curry a day, some other dry fruits and not the other fruits. Also I have got protruding belly which I really really hate. I have been going to gym for one hour in evening since last 30 days, and doing all the random exercises related to protruding belly.

Edit: protruding belly is probably because of bloating issues, I used to burp all the time but burps are almost nil after one month random abs workouts