I think it's called a signature, but you have it after you type something. It can be an image or video. How do I get one from my computer pictures?
Go to your name (BudderChar) left to the Inbox button, click that and you will see 2 rows. On the first row, the second word you see "Signature", click that and done.
You need to upload the image to website to get a shareable link, then you would click the picture button. I usually upload mine to imgur, so you could try using that.
Also, you could use URL shortener if the link seems too big. That's what happened to me, the links for my sigs were too big so I used the shortener.
