Once you have found the Service you wish to request, it is a matter of filling out the fields requested on that form and clicking the submit button in the lower right. Note that required fields on the request will be indicated, usually with a red star by the field name.
If you get partway through filling out a request and realize you don't have all the required information or for any reason can't or don't want to submit the request right now, you can click on the save button to save the request for later. This will make the request available in you "My Requests" section as a draft.
One of the options when reviewing the status of a submitted request is to "Clone as Draft". This will make a copy of the existing request and put it in your drafts (and take you to it). This allows you to make very similar requests repeatedly without having to start from scratch.
After you submit a request, the information provided is passed into a workflow process.
The progress of your request can be viewed under "My Requests" for your open or closed requests.