Hi!
I would be tempted to say: Just follow the arrows. But here his the actual way:
Rua Dos Concheiros, rua de San Pedro, Porta do Camino, rua das Casas Reais, rua das Animas, plaza de Cervantes, rua de la Azabacheria, Arco del Obispo, Plaza del Obradoiro.
Cheers,
Jean-Marc