How can i get writing a novel?

I want to write a novel! BUT...I CANT! I try, and I try, I have a million ideas in my head. I feel the DESIRE to write. The neeed to write. Seriously its that bad. I want to write write write. But when I go to, I freeze, blank page, pencil touches...

page, pencil scribbles on page, page now has a black dot, no writing at all. HELLLPPP! please..

try not to think about it to much.. go outside to a park or something, somewhere, where its quite and you can just think