We earn merit by providing constructive and helpful posts to the community or by providing services which can be found in the services thread.
Constructive and helpful posts do not mean finding random articles online and posting the content here. You must include something original and new for this for be constructive and helpful, whether that be new insight on the resources you're providing or just asking additional questions about the content. Even adding a bit of your own personality brings something to the community.
Im not really sure that we can earn merits with our constructive and helpful posts only, because I have read posts that helps and still ignored because givers are saving their merits to the best post only, which are done by the veterans here. Even if assuming I can post a good one, I think there's a little chance I'd be given a merit.