So Here's a bit of advice when you're drafting.
First create your mental quiet zone. Unplug the phone, get the kids occupied elsewhere. Do something to let your brain know it's time to write. Put on some favorite, quite music, chant a mantra, whatever it takes to set the stage and give the signal it's time to begin.
Then, don't begin actual drafting until you've created an outline of some sort for yourself, you know, a plan. Doesn't have to be formal, just something that points the way. Know your characters before you begin, maybe keep a notebook page on each one. You don't want to have to ask yourself, "What is my protagonist, John Smith, going to do?" You need to know how he'll react. Know the story you want to tell. Hopefully have an ending in mind, where you want to take your tale. Make notes by hand or in a digital file so you can remember where you're going later after you're hot and heavy into your story and maybe you lose track of exactly where you intended to go.
Okay, ready to get some words up on that screen? Now is the time to keep in mind that drafting is not about quality, it's about getting that story down on paper (or up on the screen). It's about getting it out there. Don't make yourself crazy about details here, just get the story in your head onto the page. Use placeholders, whaterver it takes to get the story down. Don't allow yourself to linger over every phrase or to continually go backwards to tweak what you've already written. Keep moving forward. You can always toss notes into you draft in parenthesis (those placeholders I mentioned above) or using the note function of your word processor. Then worry about those changes and additions later, in the next, polishing draft. Constantly going back means you'll never finish the novel. Again, keep moving forward.
And finally, make writing a habit. Set aside definite times when you can write and stick to it. And when you're writing don't allow yourself to be distracted by anything on the web. Don't open a browser. Create goals for yourself whether it's so many words or an alloted amount of time and unless there's an emergency like your kid just fell off the roof, stick to it.
There, that's it. That's how to get your first draft out there. And actually, it's the easiest part of writing.
Now go write something.