If you are able to edit the HTML that gets saved to the website then adding a link is easy. HTML code is just simple tags that wraps text. A tag is made up of angled brackets - < and >. For example to make something bold you would type:
<b>this would be bold</b>
Note that the second tag has a / in it. This means that it is a closing tag, so anything within the opening and closing tag will be bold.
To make a link to another website you would use the Anchor tag:
<a href="http://www.activeunlimited.com/teacher/auadmin">Private swim teacher in Bondi</a>
which would display as:
Private swim teacher in Bondi