How do i turn on a skateboard?

i mean i know how to turn but how do i turn while im in the air. i can't ollie ive dont everything but still no. does doing an ollie have anything to do with it? i can turn but it only turns around 90 degrees i want at least 180. thank you. oh and can you put a link of how to do an ollie? and i need something that actually works!!!!!!!!!!