Yes.  Click on Settings at the top of the admin panel and click Library Banner.   Click on Choose File and upload a new banner.  The image that you upload should be 960 pixels wide.  The height does not matter but you do not want it to be too long or too short or the pages will not look good. The average height is between 150 - 250 pixels.  Your landing page will update automatically.  You may need to refresh your page to see the changes.