Look through the info here firstly:
In configuration file of postgreSQl server pg_hba.conf you need to add IP-Address of PC you want to connect from (without password) with the following values:
|host||all||all||127.0.0.1/32||trust||(for current machine)|
|host||all||all||127.0.0.1/24||trust||(for all IPs within network)|
If you set up md5 method and not TRUST you need to specify password.