You need to explain them not just the music thing... some small things related to it...
On the 2nd Monday of ramzan, we had a daw'ah programme which many non-muslims attended. Among the main questions that were asked, one was "Why do muslim women wear burqa ?"
I thought that the replay would be "to protect modesty"
But It was not so. The reply was very very higher grade than I expected, he replied in a looooooooooong way,
"In the world you see everywhere so and so things going on, many people in western societies are living a horrible lifestyle, in europe, the very concept of family has been demolished..." so and so he went on saying many problems of not wearing burqa, then he said even the Bible says "whoever looks at a woman lustfully, he has committed adultery in heart" then he finally started saying that Islam cuts the roots of all these relation be protecting gaze, men should lower gaze and women to wear burqa, etc
So it was a very long and detailed answer for a simple question (most muslims might think of it as a simple question)
Similarly, tell them about Music.. what is the modern position of music,, how people are becoming addicted to it, how it is becoming the cause for so and so .
These articles might help you:-
And anyway google search is always there for you.
Inshallah. I pray for you that you be able to succeed in Amar bil Makruf Nahi anil Mungkar, as very few muslims are practicing it today....
May Allah reward you.