To get started Select Lists from the main menu and then Comms.

If the airport is a stock airport then there will be a list of comms shown.  Not all of these will be for your selected airport

1. Comms that have a black icon next to the are for the airport.
2. Comms that have a grey icon are those located at nearby airports.  ADE displays nearby frequencies for information. You should not use a frequency that is in use at a nearby airport.

If all the Comms have grey icons then there are nearby airports but the airport you are working on has no comms currently.

If you have created your own airport that is not in the FS stock list then you will see an empty Comms list.  ADE does not check nearby airports when you create a new airport.

Click the Add button at the bottom of the List dialog.

The Comm Properties Dialog will open.

Enter a name for the Comm.  It is usually the airport name

To get ATC at an airport you need to have a Tower frequency so from the drop down list select TOWER.  

Now select a Frequency from the drop down list.  Using the list ensures that the frequency is a valid Comm frequency

Click Save to save the new information into the ADE project

The new frequency should appear at the top of the Comms list with a black Icon indicating that it belongs to the current airport.  You can now close the Comms List and compile your airport to check that the frequency

When you add a Tower frequency to an airport this will enable ATC.  However this will not ensure that ATC will announce itself with the name of your airport.  To do this you will need to edit the voice information in FS.  This is outside the scope of ADE.  However there are tools that  can help you do it.  Alternatively you can ask for help on http://www.fsdeveloper.com.  Someone there will be able to help.