Recompile and update old C++ source

We have some C++ source code from early 2000we need to recompile to get it up and running on a new windows machine.
It is a server software that receives text files via FTP and creates packages in two different formats for download for users/clients. It also has some features for user account administration.
Task to be done:
1. Recompile and make it run on a mocern windows server version (accessible from Internet).
2. Document functions and headers so we can modernize it.
If the project is successful, more projects will come to develop the source code.