You can change a number of options in Gmail, from the theme that your mailbox displays, to mail forwarding options. The Settings screen is also used to manage labels and filters.
All user preferences in Gmail are changed by clicking on the Settings cog near the top-right corner of the screen.
The most commonly used settings are listed in the Quick Settings pane, including the theme you wish to use in Gmail, your Inbox styel and reading pane settings.
To view all Gmail settings, click on the See all settings button at the top of the Quick Settings pane.
Use the General tab to change your language preference, the number of conversations to show on the screen, and other useful options such as your signature and Out of Office reply
Use the Labels tab to manage labels to keep your Mailbox organised
Use the Inbox tab to set the style of your Inbox and choose which categories to display
Use the Accounts and Import tab to access email from new email addresses, or to delegate your mailbox
Use the Filters and blocked addresses tab to set actions to be carried out on messages as they are received
Use the Forwarding and POP/IMAP tab to forward messages to another email account if you are unable to access Gmail
Use the Chat and Meet tab to set chat options such as whether your chat history is saved, and whether sounds are enabled to notify you of new chat messages
Use the Advanced tab to use advanced, experimental features that are not yet part of the core Gmail application, such as templates and custom keyboard shortcuts
Use the Offline tab to enable access to Gmail when you are offline
To set a theme to control the overall look and feel of Gmail:
Click on the Themes tab in the Settings screen
Click on the Set Theme link
Choose the theme you wish to use
Click on the My Photos button to select an image from Google Photos or to upload a photo from your computer to use as a theme