Argh, Help please in using screens and Graphic Layout Editor

So basically this is what I have to do.

1. Implement your main selection screen with a parameter (recommended: call it PA_INPUT) of type C and length 20. It should appear on screen as "My Input".

2. Upon execution, you will have another screen (say screen 100) that will present two options:

2.1 Display input as a list

2.2 Display input in a screen

3. If a user selects the first option, write the input made in the selection screen as a list.

4. If the user selects the second option, write the input made in the selection screen onto 2 separate fields on screen. Both fields are OUTPUT only. The first field will display all the characters in upper case, and the second in lower case.

So far my code has this.

REPORT ZISTANZS_TRNG_EX7AA.

PARAMETERS PA_INPUT(20) TYPE C. .

CALL SCREEN 0100.

It's not much I know. But I have basically no idea how to use screens. Reading on the tutorials, I've managed to create a screen 100. Editing its layout to have 2 radio buttons DEFINED as well as having a text beside them Display input as a list and Display input in a screen. I also manage to create a Pushbutton with Name of ENTER and text as ENTER with a function code of 110.

Now, I don't know how to proceed. Basically I'm stuck here. I keep reading this tutorial my supervisor gave me but her instructions were so vague that I ended up confusing myself. I know it may have something to do with modules but I don't know how to implement it. I'm not sure how I can know if the user chose to display input as alist or screen and I don't know how to seperate them? Any help or even jsut tips on this would be appreciated. and also given points.