Recently a parent asked me to help her understand the scoring of the PSAT. One of the first questions I asked her was what test her learner took. There are several tests with PSAT in the title (including PSAT8/9 and PSAT10), but only the scores of one test--the PSAT/NMSQT--can be used to qualify for the scholarship. Students usually take the PSAT/NMSQT in the Junior year. There are exceptions to this requirement of which parents should be aware.
Though we talked about several aspects of the test and scoring, I encouraged her to connect with several reputable sites so she could better comprehend not only the scoring but also the National Merit Scholarship competition.
First, I pointed her to several online resources which explain the scores of each of the PSAT tests: the Duke TIP identification program, the College Board's explanation of the PSAT8/9, the College Board's explanation of the PSAT10, the College Board's parent tutorial for scoring of the PSAT10, and the Princeton Review's scoring guide.
Second, I encouraged her to learn more about the NMS competition itself. I pointed her to the National Merit Scholarship Corporation's website where she could read about how to enter the competition.
Third, I encouraged her to look over the Student Guide of the National Merit Scholarship Program. This guide is usually sent to school guidance counselors. Because the mom who asked me about scoring was a homeschooling mom, I knew she would be acting as her learner's guidance counselor (of sorts) and thought the guide would be helpful.
With these resources at her fingertips, the inquiring mom could find the answers which best paralleled the unique questions she had for her learner. Working with hundreds of parents, one thing I have come to understand is that though there are some general questions most parents ask, parents also ask very specific questions based on the individual circumstances of a learner. Perhaps your questions are both general and student specific.