You can use the Web Savvy – Button Widget in any of your sidebar locations. Our theme demo shows it in the sidebar of the blog posts and pages.
To use the widget go to Appearance –> Widgets and drag an instance of the Web Savvy – Button Widget to the appropriate sidebar. Fill in the Title field with the text you want to show. In the Link field enter the URL you want the button to link to.
Remember to click the Save button to lock in your changes.