Left click & hold at the start of the link and drag the mouse to the end of it.
Hold down the 'Ctrl' button on the keyboard and then press the 'c' at the same time.
Go to the signature box and click you mouse in it then press 'Ctrl' and 'v' and the link should appear.
Then make the changes as above.
You might find it easier to open 2 windows - one with this page and the other with your profile page.