Question about PSAT scores?

I'm an 8th grader in California and I just got my PSAT scores back but don't think that they're that great even though people keep telling me they are. I got a 161 for my Selection Index 50 for Critical Reading. 55 for Mathematics. and 56 for Writing Skills. Do you think that's good? I can't tell. What does that rank me as for an 8th grader? I wish my scores were in the 70's instead of the 50's. The 50's feel like failing.