For some reason, I need to open my VPN connection in command, who know how to do this, thanks!
The short answer is it depends.
The long answer is that it depends on what you are using. For example, from looking at the Cisco VPN documentation, the arguments used at the command line would be something like:
.../vpnclient.exe connect exampleprofile.pcf user pwd
From here (http://www.cisco.com/en/US/docs/security/vpn_client/cisco_vpn_client/vpn_client46/administration/guide/vcAch5.html#wp1159280). Obviously, with different software, you may have to use different arguments. Try running the program without any arguments or with the "/?" or man switch or command depending on your operating system.