Put the url of the link you want in the box. When you click on OK, you will be taken back to the thread with the middle of the link highlighted. Type the words you want the link to appear as in the highlighted section.
Example:
Click on insert link, type Freeones. com (without the space) as your url.
type "Freeones Home Page" in the highlighted portion and after you click OK and you should see this:
Freeones Home Page after you exit your post.