<p>I'm trying to create a new Excel file using jxl, but am having a hard time finding examples in their API documentation and online.</p>

Not sure if you need to stick with JXL, but the best library for handling Excel files is
Apache's POI HSSF
.
I think there are plenty of examples on the website I provided, but if you need further assistence, let me know. I may have a few examples laying around.
Just out of curiosity, POI stands for Poor Obfuscation Interface and HSSF is Horrible SpreadSheet Format. You see how much Apache loves Microsoft Office formats :-)