You asked a really good question, it's good to ask to seek knowledge so you won't make mistakes, most Newbies would be wondering why they don't get merits, and if there's a required number of posts to be merited, I thought about that as well when I earlier came into the forum, but no there's no required number of posts for one to be merited.
 
 The major requirement for getting merited is creating good and quality posts, when you create good post, by teaching, giving good replies to a post or even questions whereby other members could learn from, maybe anyone who have Smerits and is pleased with your post or a merit source could merit your good quality post.

 Also if you check the beginners board, there's a thread by @fillippone where people could share their best post to be merit assessed, there's another thread by @hugeblack where you could share your best local board post and get merited, I think there's another one by @NotATether in same beginners board where you could run a node for 14days and get merited. But you should know that before you share your post in those threads they should have quality and also follow their instructions so as not to receive negative tag.