Help, Site to site connection

[Gitendra]

I need some advice connecting two sites:

The main office has a Windows 2008 Server Standard Edition with
workstations connected to its domain. The branch office has its computers
configured as a workgroup and shares on a NAS storage drive.

I need to give the branch office access to the servers shares, I also need
to give the main office access to the branch offices NAS drive.

Both sites have broadband connections to the internet. Can I achieve my goal
keeping the workgroup configuration at the branch office.

Thanking you in advance.