Router Configuration (Domain)

RouterOS Beginner Basics
1

Help me to configure :
network Setup :

3g Modem (Internet) ----> Mikrotik <---- LinkSys N series Router (Wireless)<---- Client (Connet thru Hotspot)

I need the follwing further configuration

  1. I am connected to domain in office which is maintained by the Group Head office , i need to use the above connection to connect to office using same setup a different network card but to connect to vpn from internet.

Please post if u require further details