That's the part you could try to search for yourself. i'm not going to write code for you, i point to a direction you could search for. (and learn perl this way)
If a simple thing like reading a dir, and or changing / adding the filnames to an array is to hard for you, i will help.
But if you don't want to put any effort in searching for examples, show what you tried till now, i don't even want to help.