If you have ever used a computer before- then now with Mint it should be easier than ever.
You can start by reading the user guide- there should be a link to it on the welcome page.
To add software- click on software center>select category & click on it>look through software. If you see something you want-> click on it (or maybe double click)> then click install......its automatic.
I use Mint 13 at present. I tried Ubuntu Linux about 5 years ago- I never looked back. I have never been a compugeek or programmer, just a noob type user. With Mint its all point and click. If you want to go into terminal and type commands- you can.
If you can't find a link on welcome page to user guide, just go on the net any search for Mint guide.
Edit: I ordered a book by Rickford Grant a few years back. It was a project type book for Ubuntu. It taught me all I needed to know. It is similar to the one in this link-
Mint is based off Ubuntu-
Edit 2: Mint Debian (LMDE) is a different animal....it is for experienced users.
http://www.amazon.com/Ubuntu-Made-Easy-Project-Based-Introduction/dp/1593274254/ref=sr_1_2?s=books&ie=UTF8&qid=1364345543&sr=1-2&keywords=learn+ubuntu+linux