Replace Gravatar by image

Love the theme! And it works very easy. I want to use the theme to specify which CD’s I listen, which books I read and what films I watch. Because I am the only writer, a Gravatar is not necessary. That’s why I like to replace the Gravatar by another image, for example by the image of a specific CD. I know that I have to be in line 3 of entry.php, but do not know how what is the next step. That’s simply to difficult for me. Has someone an idea?