How to configure the postgresql.conf files

Hello all!
          I'm a new to Postgresql , I have never used it  before.
          I am having an issue with configure the postgresql.conf file.
          The machine itself is a
      CPU= 2.66GHz P4 w/
      Memory= 2G
          Maybe you can tell me how to configure these parameters.
          shared_buffers=
          max_fsm_relations=
          max_fsm_pages=
          max_locks_per_transaction=
          wal_buffers=
          sort_mem=
          vacuum_mem=
          wal_files=
          wal_sync_method=
          wal_debug =
          commit_delay =
          commit_siblings =
          checkpoint_segments =
          checkpoint_timeout =
          fsync = true
          enable_seqscan =
          enable_indexscan =
          enable_tidscan =
          enable_sort =
          enable_nestloop =
          enable_mergejoin =
          enable_hashjoin =
          ksqo =
          effective_cache_size =
          random_page_cost =
          cpu_tuple_cost =
          cpu_index_tuple_cost =
          cpu_operator_cost =

          Would you mind to send me a copy of examples .(postgresql.conf)
          Thanks
          Sincerely,

Chris.Wu