How to connect to a Homemade PC Minercraft Server?

I set up a minecraft server, it works fine for me but my girlfriend can't connect to it. I have plenty system specs to to do it (GTX 680, Athlon II 640, 16 gb/ram 8 dedicated to it, Win7 64 bit). I have the start.command file nessacary for it to run. Any help?

Have you tried to forward the port it's running on? If you don't allow this on your router that's my guess as to why it isn't working. (Used to have my own server a year back, but I don't know how things have changed since then)
Here's a guide I found http://portforward.com/softwareguides/minecraft/portforward-minecraft.htm
But if this doesn't work try just google 'Minecraft port forwarding' and maybe that can help.
But I can't promise you this is your problem, just trying to help

And if all else fails try looking into setting up a 'Hamachi Minecraft Server'.

Two major things:
1) Port forward on the router to the internal server IP address (IP of the game server). Any "server" should be on a PC with a static LAN IP address, so it does not change ever…
2) Forward those same ports in the Windows firewall.