Ray for 1/4 notes, everytime you hear the beat, you play the note 1,2,3,4. For the 1/8th notes, 1 and, 2 and, 3 and, 4 and... You hear the the beat on the 1,2,3, 4. So, the first note starts with 1 then you hit the second note on the and so on. So the "and" falls between the Metronome beats.
For trips, 1 and a, 2 and a, 3and a, 4 and a....... You hit the first note on the 1, your second note is on the "and", the third note is on the "a".
So your 2nd and third notes fall between the Metronome beats.
Same for the 16ths with an extra note between the beats of the Metronome. 1 e and a, 2 e and a, 3 e and a, 4 e and a.
I hope that helps Wayne could probably explain it better.