If you would like to add a "back" button to the top of your Wordpress blog, then you will need to go to Wordpress admin. When you get there, you will need to find "Thesis Options". Then, click on it. Next, find "Header Scripts" and click on it. Copy and paste the script into the box. Next, save it by clicking on the green button that reads "big ass save button". Next, go to "appearance". Then, find "editor". Click on "editor". Click "header". Add the script. The image needs to be added. Find your image. Upload it. When you visit your site, the back button should be there.