How do I open a range of ports on my Efficient 5871 IDSL Router

I have a Efficient 5871 IDSL Router (5871-001/2) and am trying to open a
range of ports, like ports 5444 to 5666, my router NAT configuration says:

WAN ----> First port, last port, then under local machine it asks me the IP
address and a default port number, but how do I open up the entire port
range to a single, or all computers on the network? Or will I have to use a
different port on the other machine on the network (I only have 2 PCs on the
network right now)

 

You'll need to use different port ranges for each PC, as opening a range of
ports on a NAT router just means you're telling it to forward packets
incoming on those ports to a specific internal IP address.
I only have general router/NAT experience, but I think you can leave default
port number blank, or set to the lowest port in the port range. I would
think that setting a different port there will remap the ports, i.e by
specifying 6444 you can have anything incoming on ports 5444 to 5666 sent to
ports 6444 to 6666 on the internal computer.