audition for jazz band tomorrow.. new..

i'm signed up for 10th grade jazz band tomorrow as a guitarist and my teacher wants me to switch chords quickly and know all of the open position chords..

and power chords..

i can't find videos over it.. probably because i'm new here.. but if anyone has any suggestions or links to excersises i would be very greatful.. i've always wanted to be a musician.

Here's a recent addition to start from:
http://www.guitartricks.com/tutorial.php?input=463

i also started playing jazz guitar in high school, but it seems that i had a bit of a leg up on you. you're gonna have a hard time playing jazz if you can't play changes relatively fast, and you need to have at least a rudimental knowledge of theory to understand extended chords so you can make them yourself. however, i guess you could just practice realllllly hard and memorize alot of them, if that will get you by....but you should really get going on this. it doesn't come very quickly.