Request for help with increase tablespace size

Hello,

I am using Oracle 8.0.6 on windows platform.

I have an Index with following info abt it:

SQL> SELECT EXTENTS,INITIAL_EXTENT,NEXT_EXTENT,MIN_EXTENTS,MAX_EXTENTS FROM dba_segments where segment_name='GLAT_I1';

EXTENTS INITIAL_EXTENT     NEXT_EXTENT     MIN_EXTENTS     MAX_EXTENTS
---------   --------------------     ------------------    -----------------      -----------
       11       17805312             516743168                   1                      121

SQL> select TABLESPACE_NAME,NEXT_EXTENT,MAX_EXTENTS/1024/1024 from dba_tablespaces where TABLESPACE_NAME='GNP2000';

TABLESPACE_NAME           NEXT_EXTENT     MAX_EXTENTS/1024/1024
------------------------------    -------------------     ---------------------
GNP2000                             102400                  2048

SQL> SELECT max(bytes) FROM dba_free_space WHERE tablespace_name ='GNP2000';

MAX(BYTES)
----------------
 480133120

When i ran the health check(TOAD) on my database, i got this warning: