i dont know how it works in your school but around my area you have to try out for the specific team to be on that team and if your really good and someone gets hurt during the season for varsity they might move someone up.
When I played, at my school,you tried out for all three teams. It was a giant tryout and based on your skill level they would placeon what ever team. If you were good enough you made varsity, if you were good but needed work you made Junior Varsity. If you were a Freshmen and were'nt good enough for either team, then obviously you made the Freshmen team. I made JV as a Freshmen, made Varsity Sophomore, Junior, and Senior years, I will be playing ball at a D2 college this year.
Nervous about tryouts?? You will learn and perfect great drills by checking out www.AimHighHoops.com for their new exciting model for player development. The Pure Shooting training DVD is endorsed by state championship coaches as well Cleveland Cavalier 3PTsharpshooter Anthony Parker. Top notch content at a very reasonable price!
At my school the head coach would put underclassmen ( 9th and 10th ) on one side and juniors and seniors on the other side. then the assistant coach watched us play and the head coach watched the Juniors and Seniors. after like 2 hours of drills the best upperclassmen and like 3 of the best underclassmen would scrimmage.