Templates are the method MODx uses to "skin" your site. They're very simple to create or adapt from existing HTML pages. But for those who just want to install templates as easily as possible, then there's SkinGraft.
This module allows you to upload a SkinGraft-ready template archive and have everything you need installed for you. It also provides tools for managing your templates, and for creating the files necessary for creating SkinGraft packages out of your own templates.