Hi Priyesh Shah,
Instead of using GUI_DOWNLOAD function module you can use XXL_FULL_API. In that XXL_FULL_API function module you can give the Header also.
Example Code.
*** Show Status as an excel file *****
DATA : header3 LIKE gxxlt_p-text VALUE 'Status',
header4 LIKE gxxlt_p-text VALUE 'Excel Sheet Format'.
* Internal table for holding the horizontal key.
DATA BEGIN OF t_hkey1 OCCURS 0.
INCLUDE STRUCTURE gxxlt_h.
DATA END OF t_hkey1 .
* Internal table for holding the vertical key.
DATA BEGIN OF t_vkey1 OCCURS 0.
INCLUDE STRUCTURE gxxlt_v.
DATA END OF t_vkey1 .
* Internal table for holding the online text....
DATA BEGIN OF t_online1 OCCURS 0.
INCLUDE STRUCTURE gxxlt_o.
DATA END OF t_online1.
* Internal table to hold print text.............
DATA BEGIN OF t_print1 OCCURS 0.
INCLUDE STRUCTURE gxxlt_p.
DATA END OF t_print1.
* Internal table to hold SEMA data..............
DATA BEGIN OF t_sema1 OCCURS 0.
INCLUDE STRUCTURE gxxlt_s.
DATA END OF t_sema1.
***** End of show the status as an excel file ********
* Text which will be displayed online is declared here....
t_online1-line_no = '1'.
t_online1-info_name = 'Created by'.
t_online1-info_value = sy-uname.
APPEND t_online1.
* Text which will be printed out..........................
t_print1-hf = 'H'.
t_print1-lcr = 'L'.
t_print1-line_no = '1'.
t_print1-text = 'This is the header'.
APPEND t_print1.
t_print1-hf = 'F'.
t_print1-lcr = 'C'.
t_print1-line_no = '1'.
t_print1-text = 'This is the footer'.
APPEND t_print1.
* Defining the vertical key columns.......
t_vkey1-col_no = '1'.
t_vkey1-col_name = 'Material'.
APPEND t_vkey1.
t_vkey1-col_no = '2'.
t_vkey1-col_name = 'Plant'.
APPEND t_vkey1.
t_vkey1-col_no = '3'.
t_vkey1-col_name = 'Start Date'.
APPEND t_vkey1.
t_vkey1-col_no = '4'.
t_vkey1-col_name = 'End Date'.
APPEND t_vkey1.
t_vkey1-col_no = '5'.
t_vkey1-col_name = 'Requirement Quantity'.
APPEND t_vkey1.
t_vkey1-col_no = '6'.
t_vkey1-col_name = 'Status'.
APPEND t_vkey1.
* populating the SEMA data..........................
t_sema1-col_no = 1.
t_sema1-col_typ = 'STR'.
t_sema1-col_ops = 'DFT'.
APPEND t_sema1.
t_sema1-col_no = 2.
APPEND t_sema1.
t_sema1-col_no = 3.
APPEND t_sema1.
t_sema1-col_no = 4.
APPEND t_sema1.
t_sema1-col_no = 5.
APPEND t_sema1.
t_sema1-col_no = 6.
t_sema1-col_typ = 'STR'.
t_sema1-col_ops = 'ADD'.
APPEND t_sema1.
CALL FUNCTION 'XXL_FULL_API'
EXPORTING
* DATA_ENDING_AT = 54
* DATA_STARTING_AT = 5
filename = 'TESTFILE'
header_1 = header3
header_2 = header4
no_dialog = 'X'
no_start = ' '
n_att_cols = 0
n_hrz_keys = 1
n_vrt_keys = 6
sema_type = 'X'
* SO_TITLE = ' '
TABLES
data = it_zmmstatus " Your internal table name
hkey = t_hkey1
online_text = t_online1
print_text = t_print1
sema = t_sema1
vkey = t_vkey1
EXCEPTIONS
cancelled_by_user = 1
data_too_big = 2
dim_mismatch_data = 3
dim_mismatch_sema = 4
dim_mismatch_vkey = 5
error_in_hkey = 6
error_in_sema = 7
file_open_error = 8
file_write_error = 9
inv_data_range = 10
inv_winsys = 11
inv_xxl = 12
OTHERS = 13.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
Regards,
Ramesh N