To insert a link you need to copy the link (called a URL) from the top bar in your browser (Internet Explorer, Firefox, Safari, or Chrome).
Type some text you want to become the link.
Click and drag across the text to select and highlight it.
Click the little link icon
Paste the link you copied into the box. Make sure you do not end up with two http:// bits
It wiill automatically generate the code that is required for the link