I know where, but how do you add an image to your bio? How do you get the link of an image you have taken on your phone?

Upload it to a image hosting site. I use imgur, but if you're on your phone, another site would be better. Once the image is uploaded, get the image link for it (this is not the webpage link, but the image's adress.) After this, go to where you edit your bio, insert image, and paste the link.