bathroom switch cord pull?

Have you already disconnected the old switch? If not make a note of where the wires connected and if its not a 2 way switch you need to connect the COM, L1 and EARTH terminals the same as the existing switch. I'm assuming by a brown wire you're referring to a bare earth? You will need to sleeve this if that's what it is.
If in any doubt at all then for your own safety get an electrician in to do the job.

Stephen
March 2009