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 a Text Element to your Service Item.
2) Enter the following into the Text Element:
<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 Text Element.
4) Save the Service Item.
5) Open the Service Item and you will see 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.