Hi,

Here's a wikipedia link that might give you some idea: http://en.wikipedia.org/wiki/Content_management_system

Here's some tutorials for WordPress: http://pelfusion.com/know-how/20-tut...dpress-plugin/

I think the main two activities that you could do under a CMS would be(correct me if I am wrong):
  • Plugin development for that CMS
  • Theme development for a CMS

I think this is a great resource for WordPress: http://codex.wordpress.org/WordPress_Lessons