First you must download your server software (I recommend McForge http://mcforge.net/downloads?cid=1). Then you should extract it to a folder on your desktop (Name or place of the folder doesn't matter). Run mcforge.exe. It should make folders and other stuff. When it's done close it. Then you must open command line, and write ipconfig. Then look for your defult gateway and copy it. Open your browser and paste it to the URL box. It should ask for Username and Password. Usually username is admin, Admin, root or Root and usually there's no password or then it is admin. When you successfully logged in to your router, look for LAN Config or something like that. You must add port forwarding to port 25565 UDP and TPC. If you don't understand how to port forward, google: how to port forward. After you have forwarded your ports you must run mcforge.exe again. Open properties and there should be a button "check ports" or something like that. If it fails your ports have not been forwarded. It it succeeds your ports have been forwarded. After you have done that go to your server properties (.properies file) look for it in the folder where you extracted mcforge.exe. Change everything to your liking. Port must be 25565. Comment if you can't understand something. Sorry my english i don't know if I wrote everything right. :)