C# beginner question

Hello,

I am looking for a program (the source code) that is a todo
reminder. What I want it to do is to post reminder messages throughout
the day as I use my computer, and to do them in sequence so that I am
reminded of tasks that I have to do.

(I get caught up in learning and lose track of time - so I want something
that will remind me while I am using my computer).

I am just learning C#.

Thanks,
James