I expect to review attempted uploads in July and make things work for some of them that didn't.
On this page you can upload a GPX file, containing either routes or tracks, then edit them as usual. The currently digestible formats are just as you would download from the main site, which should be in the same format as a route dragged off a GPS and a track such as produced by LoadMyTracks.
If you simply want to visualise data rather than edit it to create a new route you're almost certainly better off over at GPS Visualizer.
Once your GPX file is uploaded you will be presented with a list of the tracks and routes within and be able to select one for import. Should it not work fear not as I will be keeping an eye on the uploads and maybe even fix things from time to time though the odd email would help.
For the time being point, route and track names are not preserved.