The following page from w3schools has some good examples:
For this example I will create a Hyperlink which will take the end user to the Kinetic Data Web Site.
To add a Hyperlink to a Service Item you would take the following steps:
1) Add HTML Content to your Service Item by dragging the HTML Content to the desired place on your page.
2) Name your Content and Enter the following:
<a href="http://www.kineticdata.com/" target="_blank"><b>Kinetic Data Web Site</b></a>
*Note that the "target="_blank" is the syntax for opening the URL in another Window.
3) Save the Service Item (Green Save in the upper right).
4) Preview the Service Item:
and you will see something like the following:
6) Click the Kinetic Data Web Site Hyperlink and a New Tab will open and display the Kinetic Data Web Site:
*Note that the Hyperlink Service Item still appears on the First Tab above.