I've been studying story structure for a while now and it's really very interesting. When you get right down to it, it's sorta like a jigsaw puzzle that just has to be put together properly.
I'm not going to even try to do a post on structure. I don't know enough about it myself and others have done such great jobs explaining it that anything I'd add would only take away.
So...here's a great series on structure. StoryFix It's an eleven part series and he really breaks it down into easy to understand bites.
There is a LOT of great information on the StoryFix site. Next week, he's doing a seven part series on the art and craft of characterization.
Also...Plot & Structure by James Scott Bell. I LOVE this book. It's one of my favorite writing books and has a special place on my keeper shelf. Though it does spend quite a bit of time in my stack of books I'm reading. This on is really nice because it has lots of examples along with exercises at the end of each chapter to put into practice the things you learn.
Remember to set your daily writing goals and make the writing a priority. If you don't take your writing serious, no one else will either.