Calling C++ dll in a fortran program

Greeting,

A new poster here.

I am working with a C++ dll originally written for a finite element program. Because it is available open source, I decided to use it in my own FE program written in FORTRAN (.f90). 

I had mailed the developers about implementing their dll in my program and the advise that they gave me was to "create a standard C wrapper around the C++ class interface, and then call the standard C from FORTRAN".

I have been working with fortran for quite sometime now, but using an external dll is something new to me.

Would be really nice if someone could explain me what the wrapping of C++ class interface means and how it could be done.

Any help, pointer or links to tutorials to accomplish this task would be appreciated.

Best,

Shreyas