You have 15 buttons below the output control to set each ARFCN manually. Just click to turn the channels for that cell on, and click again to turn them off. If you want to start again, you can click the Clear All Channels button at the bottom. Once you are finished with the unit, click the Save button to save the changes and the SAVE button will go GREEN to confirm the signal. (Saving does take a few seconds so please be patient between each Channel selection.)