Where reporting coordinates for speed trap

Go to www.openstreetmap.org and zoom to the location of the speed trap.

Option 1:
You enter the device yourself by clicking the edit link on the top left. You need an OSM user account to do that. You can follow the tutorial to learn how to edit by yourself.

Option 2:
Press the icon with the speech ballon and the plus sign ("add a note") on the right hand side. Move the blue marker to the exact position of the device and enter a description in the box on the left (what's the speed limit, in which direction is the trap working?).