If you have arrived in Mogro via the train from Boo, follow the road from the train station up to the CA-232. On the opposite side of the roundabout there are arrows painted on the stone retaining wall, directing you to the left and uphill to rejoin the official route as it too climbs into town.
The path through town is essentially counter clockwise around the conical hillside to your left. When you get to the far end of town avoid all signs directing you to the Senda Litoral. The camino passes to the left of the Iglesia de San Martín and follows the signs to Cudón, a course which has its ups and downs.