How do i address someone my age in spanish

1. ( if you are telling them how old are you)
Yo tengo ( how old are you, only the number) años

2. ( if you are asking for their age you can use)

Cuantos años tienes tu? ( use it more with young people)

Cuantos años tiene usted?( more with elders and to be more respectful)

Eco-reto my school get involved with other students from around the world. 

Es cierto que marcos vendrá a la fiesta.