The PSAT is the Practice SAT that Juniors in high school usually take in order to prepare them for the real thing when they are Seniors. The HS should have a schedule of testing sites and times for both the PSAT and the SAT. Call the office and ask if your child is like mine and won't find out on it's own.
Back when I rode dinosaurs to school we didn't do PSAT's. We just had to take the real thing without a lot of prep work. Even my HS teachers didn't do a lot with us or have special classes like they do now to help prepare the kids.