As a preliminary test, the PSAT is designed to give you a chance to practice taking college admissions tests and to see your scores. You'll be asked the same type of questions in the same type of setting. However, unless you're applying for a National Merit Scholarship, the scores are reported only to you. Colleges and universities don't use them in the admissions process.
Rather than testing your knowledge of specific facts, the PSAT tests academic skills acquired throughout your schooling to this point. In the reading skills sections, questions test your ability to think critically about what you read, while the writing skills section asks you to find errors and improve sentences and paragraphs for greater clarity. The two math sections also focus on problem-solving skills. Most questions have multiple-choice answers, except for a few math questions that require you to enter your answer in a grid.
Practice questions are available on the PSAT/NMSQT page at the College Board website. There are samples of all the question styles you'll find on the actual test, and the answers are included. While you study these examples, take the time to read the directions thoroughly and be sure you understand them. If you have any questions, now is the time to ask a teacher, parent or college counselor for clarification. You don't want any surprises or misunderstandings to slow you down or lower your score on test day.
A full-length practice test is included in the "Official Student Guide to the PSAT/NMSQT," a booklet you can get through your school's guidance or college and career office. Set aside a block of time long enough for the entire test, and use a timer or alarm for each section. Or ask a parent to help with a clock or timer and to keep siblings quiet and out of your way. When you have finished, you can find full explanations of all answers on the PSAT website.