I use Markdown a lot at work, so it's second-nature to me. If you look between the text box you're tying responses in and the preview pane, there's a link called Markdown Styling Guide that gives all of the tricks for bolding, italicizing, and hyperlinking.

Basically, it boils down to putting the text part in hard brackets [ ] and the URL in parenthesis ( ) with no whitespace between them like this: [Link to Google](http://google.com) which will appear like Link to Google.

I did have to learn two new tricks to do that. To make the text part not link, I put a \ before the [. But then it autolinked the Google URL. To fix that I had to hide some HTML italic tags in it.