Develop a simple Windows Forms Application of your own choice.

It should take user input from one or several text boxes, perform some data manipulation, and display the result.

Your application should use at least 5 of the following features (if you like, use more than 5, and add any additional features):

1. Variables
2. Button(s), Textbox(es)
3. Label(s),
4. MessageBox
5. IF statement
6. Loop
7. Listbox
8. Array or List
9. Method(s)
10. String Processing (SubString, concatenation)