Sigh.
- Put your default gateway IP into your browser (If you don't know what your default gateway is, type ipconfig in the command prompt and it will give you the default gateway IP as well as a bunch of other IPs)
- Enter your router username and password. A quick google search told me the default user is 'admin' and the default password is either 'admin' or no password. If that doesn't work, then someone probably changed it. Try asking your parents.
- Take a look through the control panel. Find the port forwarding page. Screenshot it and post the screenshot here.