As any writer will tell you, there is little that is more frightening than a pen and a blank sheet of paper, except, perhaps, a screaming two year old, but, still, you get my drift.
The truth is that while Alexandre Dumas may terrified of the blank page, he still completed The Count of Monte Cristo. He didn't let fear stop him. He faced it and overcame it. As a pole-vaulter friend of mine says, "You have to jump the fear." He's right. It's perfectly fine to be afraid, but write anyway.
Write. Even if the first words on the blank page are: "I don't know what to say here." Or try, "If I could write what I wanted to, I would write . . . "
The first draft is always bad. So don't worry about that. Just write and keep writing. Jump the fear and make it great.