how to resize table space data file in oracle ?

Find the tablespace usage: In my case it was 99% full.

set linesize 200
select
   df.tablespace_name as "Tablespace",
   totalusedspace as "Used MB",
   (df.totalspace - tu.totalusedspace) as "Free MB",
   df.totalspace as "Total MB",
   round(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace)) as "Pct. Free",
   (100-(round(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace)))) as "Pct. Used"
from
   (select
    tablespace_name,
    round(sum(bytes) / 1048576) TotalSpace
   from
    dba_data_files
   group by tablespace_name) df,
    (select
    round(sum(bytes)/(1024*1024)) totalusedspace,
    tablespace_name
    from
    dba_segments
    group
    by tablespace_name) tu
   where
    df.tablespace_name = tu.tablespace_name
and df.tablespace_name='&TABLESPACE_NAME'
order by 6 desc;

Tablespace                        Used MB    Free MB   Total MB  Pct. Free  Pct. Used

------------------------------ ---------- ---------- ---------- ---------- ----------

PROCAPPUSER_DATA                  4689968     230352    4920320          1         99

Find out the datafile of the tablespace in my case the user was procappuser and its datafile was as below.

set linesize 200

set pagesize 200

col name format a60

select TS#, File#, name from v$datafile order by 1;

set linesize 84

set pagesize 30

         7          7 +DATA/praap/datafile/procappuser_data.308.968301311

Now resize the datafile. 

For resize:  This is how you increase tablespace actually increasing datafile size. 

alter database datafile '+DATA/praap/datafile/procappuser_data.308.968301311' resize 4805G

To increase the maxsize:

alter database datafile '+DATA/praap/datafile/procappuser_data.308.968301311' autoextend on maxsize 33605g