If you are tired of the classic Gmail look, just change the theme
Changing the background (or theme) of the Gmail interface is quite easy.
Changes can be stimulating, and in Gmail you can make the interface almost as interesting as the emails it contains, or just add a background. You can easily change these themes whenever you want.
Out-of-the-box Gmail theme options include different colors, a high-contrast theme, images (some of which may change over time), an 80s computer terminal, or classic themes such as Google Tea House or Bus Stop .
Although you cannot add your own background images to your emails you can add inline images.
Change your Gmail theme
Dress up Gmail in different colors or apply a theme with many images:
Press the button Settings on the Gmail toolbar.
Go to the tab Themes †
Click the Themes link.
Choose the theme that suits you best or choose an option Random to let Google decide for you.