the wiki article "Create a Style Project from a mockup" suggests you how to analize the process of a mockup found over the internet and it shows you how to break down this mockup in order to create the page(s), frame(s) and unit(s) templates.
Now, if you want to add more useful features like Ajax functions to your templates, you can refer to the default templates offered by WebRatio (i.e. WRDefault Style Project). In fact you can copy the code of these templates, paste it in new templates and customize them.
In this way you can begin with a complete template and add your customizations to it.