Hi Mike. There is 2 ways (At least known to me) that you can do this)
1)
Server hoster. Yes this cost money, but its worth it, and very easy. All you have to do is pay and ask for help, and BAM. Its fixed/done. I recommend Fragnet.net.
2)
Run the server off your computer. (Probably what your going to do)
Here are the steps to do that.
1: Download the server(Download from here -
https://minecraft.net/download)
2: Go to the location and open the
minecraft-server folder.
3: Open it. Find 2 files called server. Try to open one, with notepad. If it's blank, chose the other one.
4: Find the port line that says
Port=xxx. By default this is 25565. Go to
http://www.portforward.com and forward your port. This is probably best explained by following the instructions on the website, or looking up a youtube video.
Anymore questions, just ask.
