Hi,
definitely start with documentation on http://jmeter.apache.org/. There is a lot of things explained enough and there are also some examples.
On http://jmeter-plugins.org/ there are some plugins and extensions for jmeter which are good to use after understanding the basics.
For other information you can simply browse the web, there is a lot of tutorials and examples. For example on http://www.tutorialspoint.com/jmeter/jmeter_quick_guide.htm there is nice basic information and step-by-step examples.
I hope, this will help you to start.
