Q: Restore MacBook Air

I just formatted my old MacBook Pro and it worked perfectly! I used the Snow Leopard DVD to do so. But unfortunately the MacBook Air doesn't have a built-in  DVD Drive and nor do I own an external one.

So, how is it possible to delete/erase/(or whatever you call it) EVERYTHING (so it's like you just you just bought a new Mac) from my MacBook Air?

Would appreciate any help!

Albin