You've never playing volleyball before, but you want to join the high school team... that's kinda a long shot.
Try to find a volleyball club, or just find some place to take classes or join a team or something. That helps a ton. make sure you practice a lot, start working out your arms a lot, and just overall, getting in shape. To practice at home, i would recommend the volleyball pal.The Tandem Sports® Volleyball Pal allows you to practice for hours without the help of another person. It consists of a waist strap with a VELCRO® brand closure, a neoprene pouch to hold the volleyball and an elastic connecting cord. The smooth action of the cord guides the ball back to you every time.
http://www.sportsauthority.com/sm-tandem-volleyball-pal--pi-1953856.html