SQL> create tablespace ts_striped datafile '/oradb01/dbatest/ts_stripe1.dbf' size 10m,
  2  '/oradb03/dbatest/ts_stripe2.dbf' size 10m;

Tablespace created.

where /oradb01 is a filesystem on say Disk1 and /oradb03 is a filesystem on say Disk3 . Now , you can say that this tablespace is striped across two disks.

-- Now lets create a table in this striped tablespace

SQL> drop table t;

Table dropped.

SQL> create table t tablespace ts_striped as select * from all_objects ;

Table created.

-- as seen below, this table is striped across two datafiles(and hence two disks(if thats actually the case))

SQL> select distinct e.file_id,f.file_name from dba_extents e,dba_data_files f where e.file_id=f.file_id and
  2  e.owner='THIRU' and e.segment_name='T';

   FILE_ID
----------
FILE_NAME
--------------------------------------------------------------------------------
        14
/oradb01/dbatest/ts_stripe1.dbf

        15
/oradb03/dbatest/ts_stripe2.dbf

-- This is an example of manual striping and is not the ideal or very scalable of doing striping. Almost always some form of RAID is used to implement striping.