What's an "xl file"? (I do not have too much experience with Python).
If you crate your own project on Online GDB, you can upload files for your project on the top menu. "Upload" is the 2nd from the left (first being "save").
If by XL you mean Extra Large, that is Online GDB does not allow you to upload them, then I'm afraid, it will not work.
Why not just download Python to your PC and work in your own environment then? Visit https://www.python.org/