I want to help you, but I don’t really know how. Is there anything that I can do?
SITUATION OF DOUBT OR UNCERTAINTY! (SUBJUNCTIVE)
Quiero ayudarte, pero realmente no sé cómo. ¿Hay algo que pueda hacer?
PUEDA (subjunctive of poder: use in situations of doubt or uncertainty)
I have to go to the store to buy some food for dinner.
Tengo que ir a la tienda a comprar algo de comida para la cena.
I have to make dinner for tomorrow.
prepare/make
Tengo que preparar la cena para mañana.
preparar/hacer