First things first, thank you for clearly tagging your support request.
Second thing is...
How much do you understand CSS, XHTML (heck, HTML), and PHP?
To code a WP theme entirely from scratch is a difficult undertaking for someone who has limited to no background in front-end web development. Even for someone who does have background, theming a WP theme from scratch isn't entirely the same as doing just front-end web development unless the someone has background in PHP scripting as well and understand WP's code functions.
In all honesty, being that you can't figure out the first step, I get the impression that you're not a front-end web developer.
For this reason, I suggest you save yourself some time and potential headache and browse the different themes available to you and choose the theme that looks and operates the closest to how you want your theme to look and AFTER that, alter the theme to look how you want it to.
And I know for a fact that somewhere around, there IS a WP theme that operates and looks similarly to the site you linked to, SO.
It's out there!