Where to start?

Okay, I want to get started writing but where to start? It's been a long time since I've had a college writing paper graded, and I do absolutely no useful writing as a pilot. I write mostly in shorthand, notes and code, certainly not proper English that's needed for a novel.  It's been about 10 years since I've had to write anything that would be scrutinized. So what is one to do? I feel like I don't write that terribly bad, I mean it's legible but I'm scared that I'm probably quite the grammatical nightmare at this stage. I don't remember any of that crap that I should have paid attention to in English composition class. Why in the hell didn't I pay attention? WHY? I thought that was the dumbest class ever, now I need it desperately.

Do I forget it at this point and just sit down and write? Worry about the grammar later? Today, I started googling the rules of writing and use of punctuation every time I forget if something is correct or not but it's just wasting an enormous amount of time. I guess I just need to get over the fact that some people are going to say I write like a 5th grader, and I don't know how to use an apostrophe correctly.

Wow that actually helped to write that down so I could see it for myself. I am acting like a crazy person. It will take years to get this done if I don't forget it and just start writing. Screw it, grammar edits will come later. Make fun of my 5th grade writing level if you wish.