In the previously, Gmail themes were provided and released by Gmail team. There were more than 35 Gmail themes that you can choose from the Gmail settings –> Themes.
However, we can only customize the theme colors but unable to customize Gmail inbox with our own background image. That would be great if all the Gmail users are given chance to choose their own background images for the Gmail themes. Thank you to Gmail team for making our dreams comes true. From now on, you can create your own Gmail theme by selecting own background images for Gmail.
How To Create Your Own Gmail Theme with Custom Background Image
1) Login to your Gmail account. Choose Settings –> Themes
2) Select Create your own theme
3) Then you can select the background image for the main area and the footer.
4) You can choose the image from your Google Picasa or just upload a new one.
5) Remember to click Save button for new background image to take effect.
If you do not want to customize your own Gmail theme, you can still select other available Gmail themes created by Gmail team to suit your need. Here’s the post to guide you How to Change Gmail Theme .