If you have a problem just go to tutorials and guides in this section and there are plenty of guides. I have copied one for you, I did not write this props go to Suenc:
Today im going to tell you how to make your PS public through Hamachi.
When you have downloaded and instaled hamachi you need to create
a hamchi group and obtain your hamachi IP.
Write down your hamachi IP.
Connect to your Database with Navicat or a similar program.
Download Navicat
When you are connected to your sql DB open the "realmd" database.Then , on the tables open the "realmlist" table.
You will se se a couple of fields.
The only one you have to care about is "ADRESS".
That is the adress of the server, put your Hamchi IP in the field, and press the save buttom.
Now start your server and change your realmlist.wtf in your wow client folder
Your server is now online and good to go. For people to connect to server, three things are gong to be needed.
A: WoW (your patch Version)
B: Hamachi.
C: And Internet of course.
THEN
1.They have to install hamachi.
2.They CHANGE their realmlist to your hamachi IP.
3.Join your Network.
4.An WoW Acc. of course.