Create alert/ reminders

[d_stranz]

We obviously need to invest in a big hammer so we can whack these people when necessary.

[silvioneto]

Good morning,
I am developing an application to manage tasks of daily life. It needs to alert the software let I lacking a dialog, for example 30 minutes to perform that task.
How to solve this problem?
I need ideas and code if possible.
Greetings.