Below the area where you type in your message there are 3 boxes.

One the says "link URL" - here you can type in or cut and paste a web address called a URL. This is the whole HTTP:\\. . .

The second says "link title" - here you can rename the "link URL so it is named what you want it to say instead of http:\\ etc.

The last one says "picture URL" - here you can type in or cut and paste a web address that specifically points to a picture. It must be a picture ending in JPG or GIF or BMP or PNG. It must already exist somewhere else on the Internet, not TER.