Reading files in from the proper directory

[SMac2347 at comcast.net]

Hello. I am admittedly a Python novice, and ran into some trouble
trying to write a program that will pull multiple excel files all into
one file, with each file on a different sheet.

I am confident most of the code is correct, as the program runs
without any errors and I found the base of it online, making changes
as necessary for my own purposes. However, I am having trouble
specifying the exact directory where my code should be pulling the
files from. All the files are in the same folder, and I have put the
folder on my desktop. Am I correct in thinking that I need to change
the current working directory to this folder in order for Python to
read in these files, then generate my output? Or should I be doing
something else?

Any and all help is appreciated, thanks!