The best way to learn Linux is to use it. A good introductory book will help, but you won't really learn Linux or become confident in your skills unless you park yourself in front of a Linux system and start typing (and popping windows open, creating files, find your way around the desktop.
http://www.itworld.com/operating-systems/288633/how-get-your-linux-feet-wet-unetbootin (http://www.itworld.com/operating-systems/288633/how-get-your-linux-feet-wet-unetbootin)