When posting links, the trick is to use the button that looks like a U-turn arrow - and the way it works is dependent on the browser you use.

With IE, type a word or words, highlight them, then click the hyperlink button and insert the link in the dialogue box, click OK and your chosen words are highlighted and turned into a link.

With Chrome, simply click the button and enter the desired link TEXT in the first dialogue, click OK and in the next dialogue enter the actual link.  When you click OK your text from the first dialogue will show as a link where ever your cursor was.