How to view only .mp3 files without their folders with artists and albums ?

I am encoding my itunes library to a lower bitrate and the program i am using (winlame) is asking me to open files that i want to encode. but when i go and open the itunes music folder all i see are folders by artist and inside of those albums, then finally the song files. How do i just get to open all of the songs at once. It won't let me open all the folders at once...and opening them one by one will take weeks