There are multiple ways how you can get the GPX file of your trip.
If you are using Dropbox, all you have to do is link Geotag Photos with your Dropbox account, which can be done in Account settings.
Once Geotag Photos is linked with Dropbox, your trips will be automatically uploaded as a GPX file to Dropbox/Apps/Geotag photos.
More info can be found in this video tutorial: http://youtu.be/Vqbw5Aw3U90
2.Using Google Drive (Android only, coming soon to iOS)
Simply add the Google Drive account in the Account and services settings and all your trips will be automatically uploaded as a GPX file.
3. Email yourself the GPX file
Open Geotag Photos on your phone, go to the "Trips history" section and click on the Share icon next to the trip name. From there you can email yourself the GPX file of the selected trip.
4. Download it from geotagphotos.net
First of all upload your recorded trip. Than log in on geotagphotos.net with your username and password and go to "My Trips" section. Each trip can be downloaded as a GPX file.