Changing your Site Logo
If you wanted to update your existing logo and change it out with a new one, you would just want to do the following. First, you would want to start out by navigating to your Admin module-->Setup-->Getting Started-->Profile page.
Once you are inside that basic information page, you would want to look for the Site Logo setting. Once found, you would want to click on Upload Logo in order to upload a new logo. After you click the Upload Logo button, a new window should now be showing.
Logo Upload Window
Inside this new window you will want to click the Select button in order to search for the new logo you are wanting to upload. Once you have selected an image, you can click the Uploadbutton in order to upload that image. Once you are finished, you can click Save in order to update your changes.
*As a reminder, there is a logo size limit of (275 x 100 pixels) and an upload file size limit of 3MB. Your image must fall within those parameters in order to have things upload properly.
Now if you were to navigate throughout your site, you should be able to see that new logo showing on the user side and on the client registration portal.