How do I add an image to a block in Drupal 7?
This answer may seem needlessly complex to answer such a simple question, but that is because I have no interest in giving fishes away, I want to teach fishing. 

Other answers suggest you embed the image directly in the block with an &lt;img&gt; tag. Personally I oppose that solution because it's "one-off" and prevents the rest of your site's functionality from interacting with the image, such as automatic rescaling of the image.

Two suggestions:


Upload the image to a node, create a View that lists your image, and expose it as a block
Use Panels to control the rendering of your page, and add the image, also from a node


While I strongly recommend using Panels, it's usually quite complicated to setup and understand for Drupal beginners so you may want to skip that.