You can create your own adventures with FATMAP by importing GPX files.
You can do so by clicking the Create a new adventure button in your profile or the adventure creation button on the right-hand side of the screen (see screenshot below).
This will open up a new window where you will be able to select your sport and then you will have the option to either Upload a track or Draw a route.
Click Upload a track to import your GPX file and select the file from your computer.
Double click on the file or select the file and click Open.
The route will be added to FATMAP, you can then save it and add details to it (name, description, photos, and more).