Warnings aren't errors - they won't hinder your program from running. In case of deprecated warnings
: you use a feature that will be removed in future versions so the devs lable it deprecated.
It may work now, but next version it may no longer as this feature was removed - then you will get an error.
You can fix it like this:
wb.sheetnames # all names
sheet = wb["UseThisSheet"] # select a certain sheet by name
for sheet2 in wb: # or go over all sheets
print(sheet2.title)
sh = wb.active # normally sheet at index 0 if you create an empy one
Source: https://openpyxl.readthedocs.io/en/stable/tutorial.html
Here is a short example on how to create a workbook (my answer to some other xlsx question): https://stackoverflow.com/a/48782382/7505395