从perl中的文件夹中读取多个文件

I'm pretty new on perl and in need for some help, basically what I want is a program that reads all .txt files from a folder, doing the script and throw the output in a new folder with a new name. Everything works when I'm working with one file at the time, specifying the name of the file.. But I can't get it to work with all of the files in the folder. This is how far I've gotten.I'm pretty new on perl and in need for some hel