To get 1 merit this is really very difficult in this forum.
Wrong. If you're here for the right reasons, it's hard not to get merit. You have zero merits because the system was implemented specifically to weed out people like yourself.
...have join in this forum for 4 months, i take an active part in this forum but it's too difficult for me to get merit. pls kindly help me 
Merits are not to reward activity, but quality. Your entire activity is limited to posting proofs for bounty campaigns.
Feel free to reply with links to few constructive/helpful posts of yours and I'll consider sending you one.
Can you take a look at some of my post if it does not fit the rules of the system? - that some tips for new players can earn some extra money with the effort they have worked.
https://bitcointalk.org/index.php?topic=3559411.0
https://bitcointalk.org/index.php?topic=4417367.0
Hard to get a merit hard. Most of people keeping their merits as a golden. The real point is we were not at the right topics so far. However i support this Merit system based Rank system. These kind of things necessary for high quality forums as Btt.