Okay, so you want to play online. Read this guide if you wish to know how to do so.

Before you do ANYTHING, there are two files in your SMBX folder.
mswinsck.oca
mswinsck.ocx
Copy both of these into your System32 folder. System32 is located in your Local Disk, in the Windows folder.
If you don't do this, you will get a run-time error as soon as you hit connect.
Oh, and, you must run SMBX as the administrator to play online. Not everytime, but the first time through you will have to run SMBX as the administrator.
HOSTING A SERVER

First of all, you have to forward your ports . If you don't do this, no one will be able to join your server. Pick a port number and forward it.
If you need your IP so people can connect to your server, just click here here and it will give you your IP.

But, If you cannot forward your ports for whatever reason, there is a program you can download to avoid port-forwarding.
You can download it here. Download the unmanaged version.
To use this program, you must click on the 'Network' button. Then, you may either make your own hamachi network or join an existing one. If you make your own, then once your hamachi server is made, go to the editor. Then, give yourself a password. You don't use your own IP for this. Instead, where it says your screenname on Hamachi, there should be an IP next to it. People will connect to that IP. Port stays the same. Oh, and they must connect to your hamachi server as well. One last thing: Hamachi is sensitive about capital letters and stuff
Say your server is SMBx Test. And your friend is trying to connect to SMBX TEST. It won't work.

CONNECTING TO A SERVER

If your friend has forwarded their ports, and you're connecting to there server, here's what you do.
>Get them to find there IP, so you know what to connect to.
>Ask them for the port, so you can connect.
>If there is a password, get it from them.
>Pick a cursor and a character, and hit connect.
If it says "Connecting to <ipaddresshere> on Port <porthere> for a long time, it means either you or your friend screwed up somewhere while trying to connect, or your friend just didn't forward his ports correctly.
If after a while it says "Loading Data from Server" or something similar to that, you successfully connected.
If you're connecting to someone's Hamachi server, hit Network, and then hit Join an Existing Network. Then have them give you the network info, and connect to their network.
After you have done so, you should see numbers by their name under the network name. That's the IP you'll be using. Connect to that IP, along with the password, if there is one. Use default port.

Now, I hope this guide helped you, and have fun playing online.