Do you mean that you want to always start at your home town airport?

If you do then start FSX and in the top right of the opening screen you can choose a different airport, choose the one you want and start FSX.

Once FSX loads and you are at your home town airport taxi you plane to where you want to always start, then go to your aircraft fuel tab and top off your tanks.  Now press the : key on your key board, save the flight, use whatever name you want and make sure that you check the box that says make this the default flight, or whatever words to that effect that the box uses.

Now when you start FSX you will be at that airport with a full load of fuel.