The best way to learn (for me) is to use video tutorials: http://blog.themeforest.net/screencasts/jquery-for-absolute-beginners-video-series/ Have a look at that website, it was really helpful when I started with jQuery.
Here you can find best, free and useful jQuery plugins including image gallery/sliders. http://www.scriptsplash.com/2012/07/the-best-free-jquery-plugins.html