There are two basic criteria to consider when learning how to read music. Pitch and rhythm. Pitch is determined by the placement of the note in the staff. Rhythm, or the duration of the note, is determined by the kind of note it is. I will deal with the five most common notes first.
Every note has a corresponding rest with equal value.
Half notes and half rests get two beats. Quarter notes and quarter rests get one beat. Each measure begins with the downbeat of beat one. Whether a note or a rest, measures always start on the downbeat of one. Be sure to give the full value of each note.