Creating a Wordpress theme from a template

I'm new to coding for Wordpress and am trying to learn how to make themes. I'm looking to create (or basically use and modify) a free theme, which appears to be more of a template, that I found (http://ift.tt/WrdQOo) but I'm struggling to find out how to go about it.

Could someone please give me some pointers or a good tutorial? I'll gladly accept any help I can get. Thank you so much in advance!