well, there are 8 eighth notes in one measure of 4/4 time. That means there are two eighth notes per beat. a dotted note means they get the full amount of beats and then an additional half that amount.. If it is a dotted half note, then it gets three notes. If it's a dotted quarter note, it gets 1 and a half beats.
half note= 2 beats (in 4/4 time)
dotted half notes= 2 beats + (2/2=1) = 3 beats
quarter note= 1 beat
dotted quarter note= 1 beat + (1/2-.5) = 1 1/2 beats
