Seriously? You are already a Full Member and you should've already knew how Merits System works You can get Merits from other members of the forum. It is given to a deserving post. That is how you can to get Merits.
And also, posting a thread about Merit is now prohibited because it has been posted/created so many times. A topic like this has been already posted a lot of time here in the Forum and posting more threads repeatedly will be considered as a spam. Please be aware of that.
If you really want to seek for answers to your questions. I recommend you to use the search function of the thread. I'm sure that you will find something helpful.

And about this
Yes, there are some threads in Archival and Economy>>Services that gives away Merits for constructive posts. If you are confident and you think that your post deserves Merit, then go and try your luck.