So I have a question in my mind that how posting useful info get merits and how people give merits?
You will receive merit when you post something that will be helpful to other members. For example, if you make a post that enhances my knowledge or I think it can be helpful for newcomers, I will give you a merit. And your useful post can be on any topic. It depends on you, what is your knowledge, which can be helpful for other members.
Can merits be shared with each other?
When you get 2 merits, you will also get 1 s-merit which you can give to any other member.