The data that you’re editing is shared with everyone else. Please don’t
add non-existent railway lines to the map. It's *very* unlikely that local mappers would have missed a railway line in South-East England.

If you’re not sure about what you’re doing, perhaps head over to https://community.openstreetmap.org/c/help-and-support/7/none and ask a question there - I’m sure someone will be able to help you.