Well he's probably very stressed out right now. There are a couple things to consider when changing tanks:
1. Is the new tank cycled and the water declorinated?
2. Is the new tank an appropriate temp?
3. Was the betta acclimated to the new tank before releasing into the water?
4. Does the new tank have enough foliage and hiding spots so that he doesn't feel so exposed?
5. Does the new tank have a lot of other fishie residents that could make him uncomfortable?
A good way to calm down your betta that has worked for me is to isolate him in a 1 gal with places to hide, add some aquarium salt and possibly stress coat, and put him in the dark to relax for a little while. Then, when the 10 gal is set up properly, you can let him acclimate in a baggie with water from the old tank or in a floating cup before he is released into the new tank.
Hope this helps!
ps- Check the stickies posted around here about introducing bettas into new homes; there's a lot of good information out there.