problem with driver

Hi all,

I am very new to postgresql.  I am working in linux machine and I have
builtin postgres server version 6.5.2. I am able to play around with sql

through command line. But When I tried to connect through my java
application it thowing SQLexception saying no suitable driver. I tested
with both "org.postgresql.Driver" and "postgresql.Driver" including
"postgresql.jar "driver file and "jdbc6.5-1.2.jar" driver files.
somebody please help me saying which Driver we need to use to connect to
the above server. Or please let me know how to solve this particular
problem. Any commands in this issue is welcome. Your interest in this
regard is hihgly appreciated.

Thanks in advance

Davis