depends. if the notes are on the same octave in game just put both notes in the same lines. i.e.
send {d down}{a down}
sleep delayTime
sleep delayTime
send {d up}{a up}
that would play both an a and d keys in game together as a cord. and count as a single dash being done on both notes. If it requires different numbered octaves, its not going to be possible. I've made a cheatsheet that tells you the irl letter of the notes and the key to press in game as well as show you where the octave changes using the in game keys are. the i key in game is the same as the a key in the next highest octave. the in game keys are laid out like a piano so w,e,r,y,u are used for the sharps and flats of a,s,d,f,g,h,j. It sounds really complicated but its not. I am just horrible at explaining things trust me lol. my letters are the smaller non bold ones, those correspond to in game key strokes. the numbers the octave numbers in game. I hope you guys find this helpful. More people who know how to do this means more music we can all play. If you have anymore questions or need for tips just ask I don't mind sharing the tricks I have found so far.