Add a logo to your store for it to appear on the left hand side of the store header, left of the navigation.
Add a favicon to your store so that it appears in the URL field of the web browser and on shortcut icons.
Adding a logo
Site Settings > Logos > Upload Logo
Click Upload Logo to browse from files on your computer.
The logo size will be constrained by header height in the design settings. By default it appears at 40px high. We recommend uploading at 80px to account for high resolution displays.
Adding a favicon
Site Settings > Logos > Upload Favicon
Click Upload Favicon to browse from files on your computer.
The image should be a .png and 32px square.