Christie
Basically you just need to take care of routing and NAT.
1) routing - you could run a dynamic routing protocol between your 2 sites or you could just use statics. If statics -
main office router -
ip route 172.17.0.0 255.255.255.0 172.17.0.1
this will tell your main office router how to get to branch office network
branch office router -
ip route 0.0.0.0 0.0.0.0 172.17.0.2 <--- note i'm guessing what this IP is as you haven't included the main office config
the above will send all traffic to main office ie. both traffic to main office 172.16.0.0 network and the internet
2) If you have NAT setup for internet use for your users in main office then you may need to add 172.17.0.0/24 to your NAT config. It's difficult to say without knowing how you have setup NAT at the moment.
With this setup you should be able to share files between sites and have branch users get to the internet.
Jon