I try to guide you, but my iTunes is in German so maybe I use the wrong translations.. The hole process has nothing to do with the iTunes app on your device..
- Open iTunes on your PC and connect the iPad with USB.
- On the left side of iTunes your iPad should appear under the section 'Devices'. Click on the device.
- Now you should see the overview of your device an the right side.
- Above the overview a action bar appears on the top of this page. There click 'Apps'. It´s near to the Apple logo.
- Now you should see a list of your installed apps and a 'screenshot' of your device.
- Scroll down on this page until a section appears called 'File transfer' (or simular).
- This section contains a list with apps supporting file transfers.
- Select 'L4C xyz' in this list. Right of it the files of L4C will be displayed.
- Now you can copy the gpx file or the zip archiv with drag&drop on the file list.
I hope that helps..
By the way: In the next version you can click on gpx files in mails, Safari or from apps like Dropbox.