How can I export my network of tracks

Problem: your network of tracks may have gotten very huge or contains some corrupted items you can't identify. Therefore you may want to start anew or make some kind of backup.
Solution: in network tracks mode, select a range of objects and Edit > Copy these. The clipboard now contains GPX fragments of these items. You can paste that into a second TrailRunner document or into any text file.
Tip: you can also use this technique to give parts of your network of tracks to a friend for that he/she can import these segments.