On Yu-Gi-Oh the sacred cards how do you make a tribute?

In Yu-Gi-Oh!, a tribute summon is performed by sending from your hand or field to the Graveyard the number of monsters specified on the card you wish to summon. The monsters you tribute must be face-up on the field, unless specified by another card effect. For example, to summon "Gaia the Fierce Knight," you would need to tribute two monsters. You could do this by sending two monsters from your hand to the Graveyard, or you could send one monster from your hand and one monster from your field to the Graveyard.