Winsocket: Connecting over Internet

Currently my app supports only local connections. Clients can connect only if they have matching IPs. So, is there any way that can enable Clients having any IP(read: throughout the internet) not just locally to connect to my Server.

P.S. : I tried making my IP static using a VPN (hamachi) - (5.47.xx.xx) so I always have this IP, but somehow people still cannot connect. If I use my currently allocated Dynamic DNS IP I cant even connect locally though my Own PC!

Any help is greatly appreciated.

Regards,
Nisheeth Barthwal