Shift is very flexible. The 'design' button allows you to change the overall layout of your pages. For example, you can swap between having your sidebar left aligned, right aligned, or having no sidebar at all. Simply choose a page type, and click save. Your page's orientation will automatically change. From there, you can move blocks from column to column.
Most of our customers have two subtly different designs – one for the homepage, which may have an image rotation screen and service directory boxes for example, and one for the inner pages, where the content just goes directly under the menu bar. That's where 'themes' come in – you can change the design of each page to be the homepage design, or the inner design. Just go to the page you'd like to change the design of, click on the design you'd like, and click save.