Installing and upgrading help

All the sites you get information and code and packages from will give you "Conditions of Use" statements. Many of them are now using Creative Commons licensing so this essentially means that if you acknowledge where you got the bits you are using from, and do not sell what you have as entirely your own work then you will be OK.

If you are not sure, and Copyright laws around the world have become more problematic in recent years, then seek legal advice. You can use Moodle, mediaWiki and other types of PHP apps freely and even charge for the service, or charge for the materials or space you offer, but you cannot claim those as your own or onsell any of the products. You can create a Theme for moodle and sell it, if you want, or a wiki package for mediaWiki and charge a million dollars, but you cannot sell mediaWiki. It is all a real minefield these days but if you make sure you clearly identify which is your work and what you have used from other people and if selling it, then charge only for what you have done - you should be OK - but ask first...