Picasa is a photo organizing program for PC. You can download it here for free. I would first like to say that I am neither an expert on Picasa, nor do I particularly like it, but it's what I use. So here are a few basic tips, I don't use it for much, mostly just for viewing my images, but perhaps other people will add to what I start.
The main reason I liked Picasa when I first started using it was that if you move an image around in your folder system, Picasa will track it and change the location in the program as well. It basically just reflects your folder system. Previous to this I had been using iPhoto on my Mac, which I felt royally screwed up my photos with some crazy folder system that I had to spend a lot of time redoing. I like that this doesn't mess with my folders and just reflects my changes.
When first installing it, there are a couple key options to get right. First go to Tools -> Folder Manager
This will bring up this box where you can select what folders you are viewing images for. So you can use it just to view your digital scrapbooking folder if you want (that's what I do, since I use Lightroom to edit my photos).
Also, go to Tools -> Options. Here you can set what file types Picasa will show you.
Some other quick tips. If you're looking for the tag window, click on this icon:
Also these little icons show you how you view your folder system. You can see I have the one on the right highlighted which personally I like much better.
That's about all I have for now. If you have any questions or advice, feel free to leave it below!