DATA : gt_table TYPEtable of gt_data.,
gw_line like line of gw_line.
FIELD-SYMBOLS: <gfs_line>,<gfs_line1>,
<gfs_dyn_table> TYPESTANDARDTABLE,
<fs1>.
* Assign the new table to field symbol
ASSIGN gt_table->* TO<gfs_dyn_table>.
ASSIGN gw_line->* TO<gfs_line>.
loop at itab into wa_tab.
ASSIGNCOMPONENT'FIELD1'OFSTRUCTURE<gfs_line> TO<fs1>.
<fs1> = wa_tab-field1.
UNASSIGN <fs1>.
ASSIGNCOMPONENT'FIELD2'OFSTRUCTURE<gfs_line> TO<fs1>.
<fs1> = wa_tab-field2.
UNASSIGN <fs1>.
APPEND<gfs_line> TO<gfs_dyn_table>.
clear : wa_tab.
CLEAR: <gfs_line>.
ENDLOOP.
Check this link, it explains clearly on how to populate a table using field symbols by looping through another table.