This is an irregular verb. It follows the conjugation pattern of the verb incluir.
PresentPresente
Cada mes contribuyo con dinero a una ONG.
Every month I contribute money to an NGO.
PreteritePretérito indefinido
Todos contribuyeron con algo de comida a la fiesta.
Everyone contributed some food to the party.
FutureFuturo
El parque nuevo contribuirá a la vida del barrio.
The new park will contribute to the life of the neighborhood.