Install Tunnelblick software: Double click on Tunnelblick installation file then double click on Tunnelblick icon to start the setup.
Click “Open” to continue the installation.
Type your computer username and password to allow Tunnelblick to be install.
Tunnelblick was successfully installed then double click on downloaded vpn profile “AIT_Net_vpn_ait_ac_th.ovpn”.
Choose “All Users” to allow all users in your computer to use this vpn configuration or choose “Only Me” to allow only your user to use this vpn configuration.
Type your computer username and password to allow Tunnelblick to make changes on your computer.
VPN Configuration successfully installed.
Start using VPN Connection: Click Tunnelblick icon and choose “Connect AIT_Net_vpn_ait_ac_th”.
Type your AIT username and password then click “OK”.
When the connection is successful, the icon will change from to
To disconnect from VPN, click on Tunnelblick icon then choose “Disconnect AIT_Net_vpn_ait_ac_th”.
to 
