First of all you need to have a fixed IP address on the PC (or PC's) that you are using to download.
Do this by going to the settings of the network connection (right click the icon in the system tray, select status then propertie). Select the Internet Protocol(TCP/IP) setting and click properties. Change the "obtain an IP address automatically" to "Use the following IP address". Enter an IP address of your choice (your router will probably be 192.168.1.1, so a good choice for the first PC would be 192.168.1.2). The subnet mask should be 255.255.255.0. The default gateway will be the IP address of your router (probably 192.168.1.1). Change the "Obtain DNS server address automatically" to "Use the following DNS server address" and enter your router IP in the first box.
Repeat the above on each PC that will be used for downloading.
Now fire up the admin tool of your router (usually by using a web browser pointed at the IP address of the router).
Go to the "virtual servers" or "port forwarding" section. Enter the IP address of the PC, followed by the port number assigned to the P2P application on that PC.
NOTE: EACH PC MUST USE A DIFFERENT PORT NUMBER FOR THE SAME APPLICATION. For example, if PC1 uses port number 3074 for Azureus, PC2 must use something different such as 3075.
You may alsoneed to specify the port numbers and IP address under "special applications" if your router has such a setting.
