The simple answer is that you can just drag and drop the HDF over the Media tab of the editor. So the first step is to create a new title (select File/New or copy an existing one), then go to the Media tab and add the HDF.
If the HDF is not bootable, a number of bootable drives are just one click away in the same tab.
Feel free to let me know what you don't understand, and we can work from there.