In Automator, click the Automator menu.
Choose the "Display Automator Website" menu item.
Your browser will go here:
http://www.macosxautomation.com/automator/
Look around on that website. Here's the section on Services:
http://www.macosxautomation.com/services/
I strongly suggest learning how to make services that perform simpler tasks, rather than immediately trying to make the service task you want. This will teach you principles using known working procedures, which you can then apply later. Metaphorically, learn to swim in shallow water before jumping into unknown waters.