I want to know how Bitcointalk forum works, in terms of merit, joining a campaign, rules and regulation.
You already have earned 5 merits so you might be aware about the same and now you only need 30 activity for your next rank of junior member but there are lot of such threads so avoid them at first.
Use search function or direct google optimized search is better for posts like this
How to rank up bitcointalk
Merits system bitcointalk
Rules and regulations bitcointalk
Bounty campaign bitcointalk
So you will get your answers as soon as you try to find them out but if you really want to rank up on forum and learn new things joining bounty campaign is not the correct way and focus on quality posting and learning on the forum first of all rather then taking earning opportunities only.