To add a signature to your Google email address, first ensure that you are logged in to your inbox.
In the upper right corner of the screen select the gear shaped menu, and choose "Settings"
After clicking on "Settings" navigate down the page until you see the "Signature" category.
In the "Signature" category select the "Insert Image" option (looks like a mountain)
From here select the "Upload" tab, and then you can either browse your computer or drop your signature into the dialogue box.
Note: If you do not see the upload option follow the instructions
here: http://support.classicalacademy.com/solution/categories/4000042988/folders/4000066976/articles/4000027237-google-unable-to-add-gmail-signature-or-signature-shows-as-a-broken-link
Hit "Select" on the lower left, and you should have a working signature!
If you need further help please submit a ticket to the appropriate email for your site.