There is an upload GPX track function on the website. You then draw your paths with the online editor, above those tracks. Edit: you do this because GPS is not clean enough and you need to choose which paths connects where.

You will often forget the details if your GPX are old. E.g. was it really possible to use a bicycle on that path, did those two actually connect or was it me running 150m through the Forrest as a short cut.

So it takes work to get right.