Look at some of the free online tutorials and follow them through. Check that you can get them working, play around with making changes and understanding what they're doing.
Alot of your early development will be in getting scripts from sourceforge and other script libraries and getting them to work. Start with easy things like magpie and get and rss feed to show on your page.
Have some fun, but remember you have to get your hands dirty, you can't just read.