How to get the field descriptions of a table?

Descriptions:
I need to get the associated data element descriptions of all the fields in a table.  I think there's a way to do that using the SELECT statement. 

Can you please give me in detail, the various steps and methods to find the corresponding SAP tables and fields for a particular transaction code, for example (CS03). 

Ans:
Do the following 2 steps. Then create your ABAP program accordingly with the SELECT statement.

1. From table DD03L, give your tablename and get all of its field names and corresponding data element names. 

2. From table DD03T, get the description of each data element you have got in step 1. 

Then Use Function Module DDIF_FIELDINFO_GET 

The sample program will look like this:

REPORT ZTABLEFIELDNAME.
TABLES: DFIES,
        X030L.
DATA: BEGIN OF INTTAB OCCURS 100.
        INCLUDE STRUCTURE DFIES.
DATA: END OF INTTAB.
PARAMETERS: TABLENM TYPE DDOBJNAME       DEFAULT 'MSEG',
            FIELDNM TYPE DFIES-FIELDNAME DEFAULT 'MENGE'.
      call function 'DDIF_FIELDINFO_GET'
        exporting
          tabname              = TABLENM
          FIELDNAME            = FIELDNM
          LANGU                = SY-LANGU
*         LFIELDNAME           = ' '
*         ALL_TYPES            = ' '
*       IMPORTING
*         X030L_WA             = WATAB
*         DDOBJTYPE            =
*         DFIES_WA             =
*         LINES_DESCR          =
        TABLES
          DFIES_TAB            = INTTAB
*         FIXED_VALUES         =
        EXCEPTIONS
          NOT_FOUND            = 1
          INTERNAL_ERROR       = 2
          OTHERS               = 3.
      if sy-subrc <> 0.
         WRITE:/ 'Field name not found'.
      endif.
      LOOP AT INTTAB.
         WRITE:/ INTTAB-TABNAME, INTTAB-FIELDNAME, INTTAB-FIELDTEXT.
      ENDLOOP.
*** End of Program 

OR

Step 1. 
Run the transaction and click on System -> Status. Note the program name shown under the transaction code. 

Step 2. 
Run SE49 and enter the program name you identified in step 1 (SAPLCSDI) and then press enter. 

This will identify the tables used, however, as you want to know the fields used as well then you may have to resort to looking at the actual code (get a developer involved if you're not one) using transaction SE80. 

In this case the transaction CS03 is assigned to a screen with a function group so it's a slightly tricker process, hence the need for a developers service. 

For all the tables, descriptions and fields you can refer to these tables:
DD02L : ALL SAP TABLE NAMES
DD02T : DESCRIPTION OF TABLE NAMES
DD03L : FIELDS IN A TABLE.