Adding a signature has to be done by you on your own account, we cannot set a signature globally!
1. log into Gmail if you follow the images below - go to Settings - top right corner
2. Then click - see all settings
3. Scroll right down the page on the General tab until you see the signature area. Click create new, give it a name and and then copy and paste the info you want to append to emails as shown below.
4. Just check the Signature defaults and select your new signature to append to new emails.
