Randomly choose arrays and duplicate movieclip?

I am wondering if someone could please tell me how I could do the following with actionscript:
onload of scene randomly choose a category (which is in an array) and match that category with the right subject (which is also in an array). Then duplicate a movieclip to amount of letters in the matched subject? I have been searching Google for the answer however got nowhere. I don’t want you to write the whole code for me. All I want is someone to guide me. Thanks in advance.