PSAT scores... Help, please?

I'm a junior, and I got a 187 on my PSAT/NMSQT, and I wanted to know how it can help me. My projected SAT score is 1870, right? So, how can this help me out? What do I need to do for the National Merit Scholarship? What should I do? My scores were 65 in Critical Reading, 57 in Math, and a 65 in Writing Skills.