![alt text][1] You *cannot auto "convert"* it in iD.
A road is created by drawing a line over a trace, You have to use the trace as a background for drawing a road. you cannot auto "convert" it in iD.
road.
If using a PC follow these steps
steps:
1. connect the device with the gpx file
2. zoom in on map and click edit choose ID
3. click in the item on the right hand side the looks like a pile of papers ( layers)
4. scroll down list to the end and click gpx files
5. find the gpx file and drag it on the map
6. Do you see the trace? good
7. Now use the line tool to draw your path or road over the trace
8. Tag it as road or path and name it if it a a name.
9. Is it all OK then SAVE it.
![screenshot of iD][1]
when I have time I'll see how it works on a Android Tab
[1]: http://help.openstreetmap.org/upfiles/ID_editor_gpx_trace.JPG