Launch Popup Every 15 Minutes in C#

How to show a popup every 15 minutes

At first you have to wait 15 multiple minutes according to your system's clock such as 15, 30, 45, 60 minutes.

Suppose you'll run a program in your system at 9:50. You will have to wait 10 minutes for first time then it'll come after every 15 minutes and and stayed for 1 minute.