You don't have to, but if you want it to say something like "Smoky's spreadsheet", open your spreadsheet in another tab, then go to your signature and delete it
Enter "Smoky's spreadsheet" in your signature and then go back and "highlight" it (like you were going to copy it)....then actually copy the link to your spreadsheet from the other tab, go back to your signature and click on the icon along the top that looks like a link in a chain (or a paperclip).....a new box will pop up to "paste" the actual link. Hit "insert" and you're done