As I recall, the Mint team actually recommends doing a clean install --- following an upgrade path is possible, but not without risk, and (again this is my recollection) the philosophy is that that risk shouldn't be hidden behind a standard upgrade procedure. So you're making a solid choice by going for a clean install.
Since you're doing a complete drive install (with no partitioning), this is mindnumbingly easy. Partitioning is just about the only thing that can possibly be confusing about installing Mint, the rest is just a matter of following the step-by-step instructions (truly the For Dummies level description you asked for, with a screenshot of every step) on pages 6-19 of the Mint 8 User Guide.
You can find the latest user guide for various versions and various languages at the Mint home page:http://www.linuxmint.com/start/helena
The English version of the Mint 8 User Guide is here:http://ftp.heanet.ie/pub/linuxmint.com/ ... sh_8.1.pdf