So is the computer you're hosting the server from going to be on a wireless connection? I wouldn't recommend doing that, if at all possible.
Are you hosting a listenserver (you make a game and play in it, it's gone when you quit), or a dedicated server? (a computer on your network hosts the game, but you cannot play using that computer) If you're making a dedicated server, there's a great site with all the information you'd need
here.
Even if you're only making a listenserver, the way to get it so others can see past your router is the same. You have to forward
these ports on your router. Depending on what brand of router you have, that'll be different. The website mentioned in that Steam answer should tell you exactly how to do it, if you don't already.
Then, once your server is up, make sure you give people your
external IP. Forgive me if that sounds stupid, but there's far too many people who can't understand why people aren't getting in their server when they give them 192.168.0.x (their internal network IP).