In order to use ATCRecall, you only need to download the latest release and unzip it at your prefered location, you can then run ATCRecall.exe.
Using ATCRecall, you can set up as many timers as you wish. In order to do so, fill the 3 fields with the timer duration, the callsign of the aircraft and the reason you put the timer, for example:
Once you have filled the fields, press the '+' button, it will start to run the timer...
When the timer reaches 00:00, it will display the 3 fields in red, and play a little sound to get your attention:
You can move any timer up by pressing the arrow up button or delete it by pressing the X button.