How do I add an e-mail signature?

To add a signature to your sent e-mails, click on the gear symbol in the top right corner of Gmail and select "Settings"

Scroll about 3/4 of the way down the page and you will find the Signature section. Once you setup the signature how you like it, scroll to the very bottom and click on "Save Changes"

If you need further assistance you can take a look at this article:

https://support.google.com/mail/answer/8395?hl=en&ref_topic=3394219