Replying to I have a problem and I need your help!!!

So I have been skiing for about 12 years and I would consider myself an advanced skier. I can the whole mountain. Except the park. Whenever I try to hit a box I bitch out and go straigh instead of 90 degrees. I can't go past 45 degrees without thinking I'm going to catch an edge and eat shit. I can hit jumps pretty well, but I want to get boxes and rails down. I see guys just hitting rails with ease and It looks so fun. Help.