To install Email Signature in Gmail on your Web, please follow these steps:
Make sure to use Chrome Browser (Safari or Firefox will mess up formatting).
Click on the 'Copy Signature' button to copy your signature.
In your Gmail, navigate to the 'Cog' (Settings) icon and select the 'Settings' option from the list.
In the 'General' tab scroll down to the 'Signature' option.
Click inside the text box and Paste your Email Signature (ctrl+v for Windows or cmd+v for Mac).
Check the 'Insert this signature before quoted text in replies and remove the "--" line that precedes it.'
Scroll down to the bottom of the page & click 'Save Changes' to save the changes.
And that's it. On composing a new email, your Email Signature will be right in place.
Good work there, you!