Prebuilt templates

I use wordpress and either use Bones or make my own templates in the child theme of twenty twelve.

How would I go about adding a prebuilt template in wordpress? Such as using a template from here: https://html5templates.com/ but then customising it.

Would it be a simple copy and paste somewhere, then adding the php calls in? (I’m not too familiar with php, just know the very basic stuff)

Many thanks Rachael