Welcome to Linux! And welcome to Mint, one of the best introductions to the world of Linux
Mint being based on Ubuntu, many Ubuntu books are suitable candidates for the new learner (like me
) So, "The Official Ubuntu Book" is a good place to start, as is "Ubuntu for Non-Geeks" -- that one features a lot of projects that Mint already has covered (like installing codecs), but is still a good introduction to many concepts. When you're limbered up and ready to take on a little more, "The Linux Bible" is a step into the beginner-intermediate world (though it's by no means the 'bible' it claims to be.)
One of the most educational things I ever did was to attempt an installation of Gentoo Linux onto a spare computer. The Gentoo manual is VERY well-written, explaining every step - and what it does and why - in plain language that a moderately new person can understand and follow. While you may or may not get a useable system after you're done, you WILL have a much greater understanding of how Linux - and your computer - works.
And lastly, hanging around on the Mint forum is a great way to learn. Sit and 'listen' to the gurus here, read posts, look at common problems and don't be afraid to ask for clarification. I've asked for hand-holding and 'talk simple for the n00b' many times and gotten it. So welcome to Linux Mint and I hope you find it as enjoyable as I have