Feliz Dia de los Santos Queridos! I have learned that the day before celebrating dia de los muertos they clean the graves and decorate for the celebration. The day after is for celebrating the dead children, and the day after that is for celebrating all dead people. They offer the dead people all their favorite foods. People dress up in costumes and they have parties and mariachi bands. They put marigolds out make sugar skulls and celebrate dead family members.