The subject pronouns in Spanish are yo, tu, el, ella, udsted, nosotros, vosotros, ellos, ellas, and udstedes. If you are talking about yourself, use the pronoun yo, which means I. If you are talking about your friends, use the pronoun(s) ellos, ellas, or udstedes.
Spanish pronouns are commonly used to best describe something on or within the person. A subject pronoun to describe yourself would be yo. Pronouns to describe a group of people would be ellos or ellas depending on if their are all girls, boys, or and both. When talking to a friend you would commonly say su meaning his or her, but saying your would be tu.