for this you still need to know the brand of your router
look up the default ip address for your type of router. chances are you've got a linksys router, and therefore your default router ip would be 168.192.1.1
default ipsnext open up a new tab on your browser and type in the default ip
for a linksys you would just type: 168.192.1.1
hit enter
if at any point you're prompted for your username and password on the next page look through this guide for the default settings for the various router brands
default usernames/passwordsfor a linksys router the default is either 1 of two things
username: Administrator
password: admin
OR (and its probably this one)
username: <blank>
password: admin
if its not one of those, ask your parents what they changed it to, but chances are they've never seen that page before in their life so the default should work.
from there get a feel for the layout of the router. its fine to look through the different tabs,
but don't change anything yet.you're looking for something called port forwarding. if you see a tab that has something to do with gaming - chances are its there (like in this pic)
it might also be under network or connections. if you can't find it post below and i'll answer.
once you get to the port forwarding page, you want to make a new rule
you can call it whatever you want, but just in case you need to go back and find it later you should call it warcraft 3
for the start of the range (which ports are going to be forwarded) put 6112. thats the default port used by warcraft 3 itself
for the end of the range put 6119.
if it asks for a base port, put 6112
under protocol choose both. if it won't let you choose both then make do this process twice, once for udp and once for tcp
choose your computer from the list of computers using the network (the changes you make only affect the computer chosen)
make sure that what you've made is enabled and make sure to click save changes before changing pages or exiting.after you finish you can close the tab