Hi,
Try Below
Here's a step-by-step guide:
Open Gmail: Go to your Gmail inbox on your computer.
Access Settings: Click the gear icon (Settings) in the top right corner.
Go to Themes: Click "See all settings" then navigate to the "Themes" section.
Choose a Theme: Select from the available themes, including pre-selected images, a dark theme, or a high contrast theme.
Customize (Optional): If you select an image, you can adjust text, vignette, and blur.
Save Changes: Click "Save" to apply the chosen theme.
To use a photo from Google Photos:
Prepare your image: Ensure the desired image is in a Google Photos album.
Open Gmail and Settings: Follow steps 1 and 2 above.
View All Themes: Click "View all" next to "Theme".
Select My Photos: Click "My photos" in the bottom left corner.
Choose an Album and Photo: Select the album containing your desired image and then choose the image.
Preview and Save: Preview the background and click "Save".