Perhaps I can help (it’s nice not to only find myself asking questions but being able to help on occasion). You add the link by including an “a href” refernece. So, looking at the html snippet that came with circumference, for the front page you would use something like:
(I guess you could omit the ‘ title=”Yourtitle” ‘ part if you like).
Button size is controlled by with the attributes: btn-lg, btn-sm, btn-xs (large, small, and extra small)
Button colour is controlled by: btn-grey, btn-aqua, etc.