You have the Garmin Nuvi 42 LM, which means you most probably qualify for a couple of free map updates. LM stands for Lifetime Maps, which for Garmin's purpose means the lifetime of the unit, not the owner of the GPS. All you need to do is download the latest version of Garmin Express and install that on you computer. Once installed, connect your Garmin to your computer and Garmin Express should ask you to add the device. Once added, Garmin Express will check for any updates and if there are any, ask you which you would want to install. Install all of those available, which should include the map update.