Changing hyperlink of header

There’s a banner across the top of my site, with an image in one place (not repeated). <www.nierenberg.com/articles> Clicking that image puts the user on the front page of the blog. I don’t want that. I want to put the user at a different address (the home page of the site of which the blog is a part). The problem, though, is that I cannot figure out how to do it. I do not know PHP, but I’ve tried to change the code in <header.php>. It hasn’t worked. What code should I put where? All help gratefully appreciated….