Having Trouble Testing Multiplayer. Any Help Is Appreciated!

The problem is you gave your friend the same IP you used, right? (That with 192.168 probably).
It is only valid in your local network, but not on the internet. It’s like being in a city, let’s say London.

Your server is in George Street and that is working pretty well…in London.
Your friend now is in Richmond, and if you say him you are in George Street, he will go to George Street in Richmond and find nothing.

First you have to give him your city, that is your public ip (http://www.whatismyip.com/).
Then, you don’t give him really the street (your local ip), but you say him a port number, like Talus showed how to configure it.
In your router, you say: “Hey, the port 7777 is of this type and should lead to this IP address/this PC” and there you give your local IP/your PC. Then it’s like “Ok, go to London and at port 7777 we will be routed to George Street”.

That’s the way it works.

Oh, the format is not 192.168.etc., it is like 95.208.248.239:7777
You append the port with a colon.

Hope I could help you with my problem, please vote if it helped you, ask if there are any more problems and good luck.
Cheers mate.