try this to restart
from linux command line - service servicename restart - make sure the service name is correct. you can type service then pos - press tab key the full service name should display then type restart.
you then need to vim the pg_hba.conf file - if only you are connecting to the database then use the postgres account you created during the installation you will be able to create other users in the database or add the users to the hba file like this
type database user ip-address method
host all all the machine you connecting from md5
the user that you add in th hba file is the user that you added to the database after connecting with the postgres account.
all means that all the databases and all the users can connect from this ip-address.