First of all login to your server, then edit phpmyadmin/config.inc.php file:
sudo nano /etc/phpmyadmin/config.inc.php
# ADD LINES BELOW THE PMA CONFIG AREA AND FILL IN DETAILS
$i++;
$cfg['Servers'][$i]['host'] = '__FILL_IN_DETAILS__';
$cfg['Servers'][$i]['port'] = '3306';
$cfg['Servers'][$i]['socket'] = '';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['extension'] = 'mysql';
$cfg['Servers'][$i]['compress'] = FALSE;
$cfg['Servers'][$i]['auth_type'] = 'config';
$cfg['Servers'][$i]['user'] = '__FILL_IN_DETAILS__';
$cfg['Servers'][$i]['password'] = '__FILL_IN_DETAILS__';