WordPress is one of the simplest self-hosted blogging platforms around, but working with multisite is a different beast altogether. Sure, there are a few online guides and tutorials, but this is just one of those things you should really read up on before diving in.
Mika Epstein, one of the top volunteers in the WordPress Support Forums, has just published WordPress Multisite 101, a pay-what-you-want eBook available in EPUB and PDF formats. The suggested donation for the book is $5, but depending on how useful you find it, there’s nothing stopping you from sending $10, $20, maybe even $100, or the inevitable nothing if that’s how you roll. The book covers everything from getting started to running your own network, and you will always have the forums if you need further assistance.