Sign into your MSOL account.
Click on "Website" to open your "Page Manager".
Now click "Edit" next to any webpage.
Once the "Page Editor" is open, click on the current website header. The "Header" tool window will open.
Since you are uploading a header with your website title and slogan, delete all text under "Site Title" and "Site Slogan".
When you have cleared all text under the "Text" tab, click on the "Logo" tab.
Click on "Upload Pictures" to upload your website header image. (When uploading do not optimize the image, or select the "Optimize" check box, as it will decrease the size of the image. Be sure the check box is empty before you continue.)
Once your image is uploaded, click on the "Logo" tab and select the newly uploaded image.
Select the "Next to Title" option, under Display Options.
Select a "Size" option, under Display Options. (Large or full size is recommended.)
After you have completed selecting the options, click "OK" to close the "Header" tool.
Now, click on the "Site Designer" tab, located next to the "Page Editor" tab.
Click on "Style" and scroll down to the 13th header option. (View Example Here)
Now, save and view the webpage. Your new header image should appear on the top of your website.
Note: Practice makes perfect. Sometimes, the header image may appear too small or too large for your website design.
If you experience this problem try adjusting the size of the image using an image program, and then re-upload the header.