Here are few quotes from well known writers that all pretty much say the same thing. If you want to write… just start writing.

“Its better to write a bad first draft, than to write no first draft at all.“
Will Shetterly

“You have to be brave to take out that white sheet of paper and put on it words that could be evidence of your stupidity.“
Sol Saks

“The scariest moment is always just before you start.”
Stephen King

“I’m not a very good writer, but I’m an excellent rewriter.”
James Michener

“Start writing, no matter what. The water does not flow until the faucet is turned on.”
Louis L’Amour

“The wastebasket is a writer’s best friend.“
Isaac Bashevis Singer

So what are you waiting for… start writing!