There are a lot of ways to do it. The hard way is to use Microsoft Moviemaker or some other movie editing software. I don't like to do it this way because it requires that you make numerous separate video "clips" and then splice them together. The easy way is to use screen capture software and then just play the clips on your video screen in the order you are going to use them, then once you have the master, you can crop out the parts of the screen that didn't have video, and edit out the sections where you were stopping the first clip and starting the next. Once you master that, then you can easily learn how to lay music into the background, place graphic effects over the top, etc. For me, the best, most user-friendly software for making videos is Camtasia. But it's not cheap. I think it runs a couple of hundred dollars. If you just want to get started, download a free version of Jing, and once you master that, then you can upgrade to Camtasia.
Once your video is produced, you have to find a video host. The three best options for that are YouTube, Vimeo and Blip.tv. I use Blip because they aren't as strict about copyrights, and I often throw copyrighted music behind my videos. Because my videos qualify as "parody" I think I could argue fair use if someone balked, but I'll defer to Oceander on that point. Once your video is posted at YouTube or wherever, you can then easily embed it on Facebook, discussion forums, etc and hope it goes viral. Blip.tv is kind of nice because they keep track of all kinds of stats, including which sites your video is getting accessed from and how many views, etc. Typically, my GOPBRTV videos get between 300 and 3000 hits, depending on whether they go viral.
If you are a novice and want to know how to do a specific thing, such as add still pics into a sequence of streaming clips, just put your question on this thread and I'll be happy to answer it. The answer to the still pics question is that you simply place the pics on power point slides and record the slides from the screen according to the planned sequence.