The framing of a basic gable roof is based on a right angle triangle and the various roof framing components fit the triangle.
Roof return framing.
The run or half the building span is the base of the triangle.
Return eaves a common roof structure is made of trusses or rafters.
Rafters start at the top of the roof and go down to the eaves but not exceeding the exterior walls of the house.
Whether you are framing a cornice return capped with a hip roof or a shed roof the first step is to install the subfascia and the ledger.
This structure supports all roof sheathing materials such as plywood sheathing underlayment and of course shingles.
Notches under the rafters allow the ledger stock to be full dimension on the ends to better support the return framing.
Run both boards long and cut in place.