A quick precis of how Openstreetmap works:
You follow a route (road, path, etc) with a GPS unit logging the trace (gpx or whatever).
You upload this trace to Openstreetmap.
You or someone else run an app which allows you to select an area, download traces and see which haven't been manually marked as roads etc. You use the trace as a guide to draw in missing roads etc and upload this new data.
So if your street is missing you can add it by either uploading a trace and then drawing the road on top, or if someone else has already traced it, you just need to do the drawing part.