Xinmayu,

There's a lot that could be said about this topic........

In short, localizers are marked on the GPS display and in Map View by green arrows pointing toward the runway they serve.  A localizer is required to do an ILS approach.

For more info on ILS approaches and a better explanation of localizers, check out Rod Machado's Ground School Handbook for the lesson on ILS approaches.  Depending on which aircraft you are flying, it will also help to be familiar with the HSI and how it functions when intercepting the localizer.

Erik

remember you need to input the correct ILS freq for the airport your approaching or it wont establish. goto map view and then click on the airport your wanting to land at and then click on it. It should then bring up the freqs for the runways. choose the right one and your on your way.