How to connect another network with VPN ?

Any way you like. VPN has mutiple types. Choose one according to your requirements.

Through IPSec tunnels in which we have some options of deployment available to choose from such as policy baseed VPN or route based VPN. In a case whereby we want full site-to-site connectivity, the route based VPN such has DMVPN can be deployed. CLientless and Anyconnect SSL VPN is also another secured option for connecting remotely to a network

through IPsec Tunnel & SSl vpn

By local & remote network

By authentication (PSK, RSA)

And with Encryption policies

It depend upon you you have options like(P2P ipsec Vpn, L2tp Vpn, Gretunnel with pptp vtp,)