SQL> desc ppimage
 Name                            Null?    Type
 ------------------------------- -------- ----
 MPPNO                                    NUMBER(6)
 MSUBPP                                   VARCHAR2(2)
 ACCES                                    VARCHAR2(10)
 IMAGE                                    BLOB

sql> alter tablespace SOMETABLESPACE add datafile 'SOMEDATAFILE' size somesize_in_megs m;

sql> alter database datafile 'SOMEDATAFILE' resize somesize_in_megs m;

SQL> connect / as sysdba;
ERROR:
ORA-01031: insufficient privileges


Warning: You are no longer connected to ORACLE.
SQL> connect sys as sysdba;
ERROR:
ORA-01031: insufficient privileges

sqlnet.authentication.services=NTS
if here specify "NONE" then change is to "NTS" then try to connect

SQL> desc ppimage
 Name                            Null?    Type
 ------------------------------- -------- ----
 MPPNO                                    NUMBER(6)
 MSUBPP                                   VARCHAR2(2)
 ACCES                                    VARCHAR2(10)
 IMAGE                                    BLOB

select table_name, tablespace_name 
from dba_tables
where TABLE_NAME = 'PPIIMAGE' or  OWNER = '&owner_of_table_user';

here you get tablespace name where table is created.

now add datafile on above tablespace.

alter tablespace &tbs_name add datafile 'location_of_file' size &put_size_according_you;

SQL> desc ppimage
 Name                            Null?    Type
 ------------------------------- -------- ----
 MPPNO                                    NUMBER(6)
 MSUBPP                                   VARCHAR2(2)
 ACCES                                    VARCHAR2(10)
 IMAGE                                    BLOB

SQL> select table_name, tablespace_name 
  2  from dba_tables
  3  where TABLE_NAME = 'PPIIMAGE' or  OWNER = '&owner_of_table_user';
Enter value for owner_of_table_user: scott;
old   3: where TABLE_NAME = 'PPIIMAGE' or  OWNER = '&owner_of_table_user'
new   3: where TABLE_NAME = 'PPIIMAGE' or  OWNER = 'scott;'

no rows selected

select d.tablespace_name, (d.bytes/1024/1024),t.table_name, (t.bytes/1024/1024)
from dba_data_files d, dba_tables t
where d.tablespace_name = t.tablespace_name
and t.owner = '&usrname'
and t.table_name = 'PPIIMAGE';

SELECT *
      FROM dba_tablespace_usage_metrics order by used_percent desc