What's blogging?

Okay, so just starting out (obviously!)....but what the hell is blogging? What am I supposed to write about? So many questions!! I have a few ideas.....maybe what it's like being a mom, but I'm sure that's been done! What it's like being bipolar. Excuse me: What it's like HAVING bipolar disorder....probably been done. Maybe parenting while have bipolar disorder? Or something more mundane, like the struggle to become a Martha-Stewart-version of myself....since I don't cook or clean, that would be a major challenge!
Is there spell check on here? Oh, good there is!!!