From your administration page, go to "Design"->"Theme"-"Layout". Drag and drop the desired number of boxes into your sidebar or body!

When you click the little down arrow on a "my image" block, you can upload an image and a link.

For the text block, you will see a text box in which you can type whatever you want, including HTML code (in 'Source' mode). These boxes are great for announcements, embeddable audio players, Facebook and Twitter buttons, and so on.

Go to the store front to have a look at your new content.