Welcome to CYS. If you have bad memory, just write your username and password down and put it somewhere where you'll constantly see it. Eventually, it'll be stuck in your mind from the constant exposure.
Since you've been here a while, I'm sure you've checked out a lot of stories, but I'd also recommend reading the articles. They're really helpful for finding your way around the forums, advanced editor, and the overall features of the website. Good luck.