requires Storage Plan, for more details see plans and pricing

In the "Homepage" tab of the "Customize" >> "Site Settings", you can set everything about your logo. The first section - "Header & Footer" provides you with links to menu designer and html customizer that allow you to change the look of your site not only for your homepage, but every page. In the same section, you can easily replace the BlueMelon logo for one of your choosing and set all its basic properties (▼).

Choosing a Custom Logo. The whole system is straightforward, you only select the choices you prefer. Firstly, you choose "Use custom logo" and a button appears that lets you select the file on your hard drive. Once you find the correct file (.jpg, .png or .gif), click "Open", and the picture will load right next to the button (▼).


Custom Logo Size. After the picture is visible, you should set its dimensions. You can also choose "auto" and the system will fit the logo to the header with 1px from borders to spare. If you want the picture to be smaller, you need to define proper dimensions. Otherwise it can extend beyond the header (▼):


The final option is to link the logo to a site. You can as easily as before choose whether you want it to lead to (Bluemelon), your bluemelon homepage (which can be on a custom domain), or any custom url. After you make your choice, do not forget to "Save" your updated "Site Settings". The final result after some 50 seconds may look like this and doesn't require knowledge of coding(▼):


What can I do next?  You may be interested in Site settings generally.