Each service is linked to a process. A process is a succession of tasks, which once completed will deliver the goal - which was the service you ordered. To start the process you need to complete the order form.
The amount of information you will be required to fill in will vary by service, it all depends on what you want to do and the complexity in the process to get you what you want.
Here's an example we can relate all to: you want to request holiday time!
Order the service named 'Holiday Request. Complete the order form, this will kick-start the process. Each person involved will get their respective task. Once all tasks are completed you will receive confirmation of approval of your holiday request (on the proviso of course that you have paid time to take off). Tah dah! Done.
You have ordered a service (Holiday Request) and you have achieved your outcome (confirmation you can take the time off).