I 'm having a difficult time with the "if statements" for a madlib in C#. Can someone please write this out, so that I may get a better understanding? Thanks

1. check to see if user put in a number or not, if not a number, show message: Input a number ---(4 out of 10 points)
2. After user hit “submit”, shows the sum of all the numbers that are in the textboxes. --(3 out of 10 points)
3. After user hit “submit”, also shows the smallest one of all the numbers that are in the textboxes. --(3 out of 10 points)