time signature is 4/4 so you need 4 quarter notes per mesure

beat 1 is the first quarter note

Beat 2 is an eight note and 2 sixteenth notes, 2 sixteenth notes counted together are the same as 1 eight note so the total in beat 2 is also a quarter note

beats 3 and 4 are every time 2 eight notes which equals a quarter note to so there you go ; 4 quarter notes in one mesure

whole note=2 half notes= 4 quarter notes= 8 eight notes= 16 sixteenth notes

eight note= 2 sixteenth notes

hope this helps Herman