This is a Classical ABAP Report for ABAP Beginners. I think it will help a lot to ABAP Beginers.

1. *&---------------------------------------------------------------------*
*& Report ZREP_004
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*
REPORT ZREP_004.
TABLES: LFA1.
TYPES: BEGIN OF T_PA0001,
EBELN TYPE EKKO-EBELN,
BUKRS TYPE EKKO-BUKRS,
BSTYP TYPE EKKO-BSTYP,
BSART TYPE EKKO-BSART,
BSAKZ TYPE EKKO-BSAKZ,
LOEKZ TYPE EKKO-LOEKZ,
STATU TYPE EKKO-STATU,
AEDAT TYPE EKKO-AEDAT,
ERNAM TYPE EKKO-ERNAM,
PINCR TYPE EKKO-PINCR,
END OF T_PA0001.

2. TYPES: BEGIN OF T_TEST,
A TYPE I,
B TYPE C,
C TYPE STRING,
END OF T_TEST.
DATA: IT_A TYPE T_PA0001 OCCURS 0 WITH HEADER LINE,
IT_B TYPE TABLE OF LFA1,
WA_B LIKE LFA1,
IT_C TYPE TABLE OF T_TEST,
WA_C TYPE T_TEST,
MIKE TYPE PFACH.
CLEAR: WA_C.
WA_C-A = 1.
WA_C-B = 'M'.
WA_C-C = 'Mayur'.
WRITE: /10 WA_C-A,
/30 WA_C-B,
/40 WA_C-C.
SKIP 6.

3. CLEAR: WA_C.
WA_C-A = 1.
WA_C-B = 'R'.
WA_C-C = 'Ravi'.
WRITE: /10 WA_C-A,
/30 WA_C-B,
/40 WA_C-C.
SELECTION-SCREEN BEGIN OF BLOCK B1 WITH FRAME TITLE TEXT-001.
SELECT-OPTIONS: MAYUR FOR LFA1-KUNNR.
"OBLIGATORY no intervals.
PARAMETERS: R_BTN1 RADIOBUTTON GROUP R1 DEFAULT 'X' USER-COMMAND UC,
R_BTN2 RADIOBUTTON GROUP R1,
R_BTN3 RADIOBUTTON GROUP R1.
PARAMETERS: CHK1 AS CHECKBOX DEFAULT 'X' MODIF ID TT.
PARAMETERS: CHK2 AS CHECKBOX DEFAULT 'X' MODIF ID MM.
PARAMETERS: CHK3 AS CHECKBOX DEFAULT 'X' MODIF ID RR.
PARAMETERS P_CARRID TYPE SPFLI-CARRID
AS LISTBOX VISIBLE LENGTH 10 USER-COMMAND LL DEFAULT 'LH'.

4. PARAMETERS P_KUNNR TYPE PA0002-GESCH
AS LISTBOX VISIBLE LENGTH 20 USER-COMMAND ONLI DEFAULT '1'.
SELECTION-SCREEN END OF BLOCK B1.
AT SELECTION-SCREEN OUTPUT.
LOOP AT SCREEN.
IF R_BTN1 = 'X'.
CASE SCREEN-GROUP1.
WHEN 'TT'.
SCREEN-ACTIVE = 1.
WHEN 'MM'.
SCREEN-ACTIVE = 0.
WHEN 'RR'.
SCREEN-ACTIVE = 0.
ENDCASE.
MODIFY SCREEN.
*
*
*
*
*
IF SCREEN-GROUP1 = 'TT'.
SCREEN-ACTIVE = 1.
ELSEIF SCREEN-GROUP1 = 'MM'.
SCREEN-ACTIVE = 0.
ELSEIF SCREEN-GROUP1 = 'RR'.

5. *
SCREEN-ACTIVE = 0.
*
MODIFY SCREEN.
*
ENDIF.
ELSEIF R_BTN2 = 'X'.
IF SCREEN-GROUP1 = 'TT'.
SCREEN-ACTIVE = 0.
ELSEIF SCREEN-GROUP1 = 'MM'.
SCREEN-ACTIVE = 1.
ELSEIF SCREEN-GROUP1 = 'RR'.
SCREEN-ACTIVE = 0.
ENDIF.
MODIFY SCREEN.
ELSEIF R_BTN3 = 'X'.
IF SCREEN-GROUP1 = 'TT'.
SCREEN-ACTIVE = 0.
ELSEIF SCREEN-GROUP1 = 'MM'.
SCREEN-ACTIVE = 0.
ELSEIF SCREEN-GROUP1 = 'RR'.
SCREEN-ACTIVE = 1.
ENDIF.
MODIFY SCREEN.
ENDIF.

6. ENDLOOP.
*SELECTION-SCREEN SKIP 5.
*SKIP 5.
*
*SELECTION-SCREEN BEGIN OF BLOCK B2 WITH FRAME TITLE TEXT-002.
*
*SELECT-OPTIONS: RAVI FOR LFA1-KUNNR.
"OBLIGATORY no intervals.
*
** parameters: Ravi like lfa1-kunnr obligatory.
*
*SELECTION-SCREEN END OF BLOCK B2.