Based on your post I am not sure if you have a 7.1 server up and running.  If not that is the first step.

Download and Install http://www.symantec.com/business/support/index?page=content&id=HOWTO9795

Install the Service Desk solution - This basically just makes the msi available to you on the Notification Server.

If you can I would start with a sandbox/dev environment to play around.  Service Desk needs a bunch of RAM so make sure you have at least 16GB of RAM and at least double for production.  For DEV just install SQL on the same Service Desk server.

The easiest way IMHO to start to play with SD and Workflow is to use the installed copy of Workflow Designer on the service desk server.  I forget the directory it put all the packages in but there will be a directory with 2-3 dozen *.package file that you can double-click and open to look at the code behind them.

If your managment wants you to implement this solution I highly recommend taking at least a Workflow Intro course because you will probably be overwelmed with making any changes within their workflows.  I built 6 in house workflows before looking at Service Desk and it took me awhile to grasp a lot of it.

If you need any help let me know.  I looked at SD for months and implemented a pilot and had to convince managment that SD was not the direction for us.  Depending on the size and requirements it may not be right for you guys as well.