create a countdown block via remote connection

how much is the cost for this? I want to do my timer, because im learning programming i dont know alot of codes and methods, then i think i can learn using this example as the image. then i need to see how is the coding part of this and some comments from the coder in order to understand the coding and methods. then basically i want to create a custom block where time configured will be a countdown timer, when this reachs to 00:00 will ring alarm even if you are using another aplications. using this part of the code i want to repeat the process adding multiple timers (i think 9 or 12, this app will be similar to some already created called @timer but i think is good start to learn) please im student, then my budget is from a simple boy