Linking an image or a banner to an item within your website is easy to do. In otherwords you could link your image to a page, product, news in your website or even an external link to another website.
For example, you may have a slider on your homepage that you would like to link each image/banner of the slide to another page within your website. This can be done on most images in pages.
In Admin go to the page where images are i.e homepage