The best way to get started is to install WordPress, install a theme, and start playing around with it. Once you?re familiar with how it works from a users perspective, then take a look at the theme code and start experimenting.
Look at the WordPress Codex:http://codex.wordpress.org/Main_Page
Read lots of tutorials like from Envato?s own WPtuts+:http://wp.tutsplus.com/
Or start with something more basic:http://www.wpbeginner.com/
There are tutorials out there for everything you just asked. A quick Google search will bring up everything you?re wanting to learn.