I have only done it a couple of times, so I'm not the expert to give you the instructions. But, basically, you design your slideshow the way you want it in the slideshow module. When you are satisfied, click on the "Export Video" button in the lower left-hand corner. As I recall, that is about all there is to it.
If you are looking for a simple way to share slideshows, and you are using Windows, you might consider trying the Faststone Image Viewer. It's free for home use. It has the capability of creating a slideshow and packaging it as an executable file that is easy to share. It's quick and easy. And because of that I prefer using it to creating slide shows with Lightroom. The only thing is that you don't have the nice background and some of those features that can be included in a Lightroom slideshow.