By default Tell a friend concerns the current page you are on, but it is also possible to point out another page by browsing to another page.
If you want the user to see the form at once without clicking a link.
If you want to have an image as a link to the form. The Description displayed under Show link will be used as alt-text, by default "Tell a friend (opens in new window)"
If you want an ordinary text link to the form, by default "Tell a friend", and default description is "Tell a friend (opens in a new window)". It is optional to type custom text. You can also select font template for the link.
If you have selected Show Icon/Show link above the form will be opened in a new window. Here you set width and height of that window.