steps
1) put in top url bar 192.168.1.254
2) then go to settings
3) then advanced then put your password in
4) then continue
5) click on portforward tap and supported applications
6) then put a name in then the ports then hit apply
7) turn dmz on and send all traphic to computer you are opening the ports on but you may not have to do this but that was the only way it worked for me but thats bt for you then apply
8)then go on to home network and click on the device you have opend the ports on and select application on there as well then apply
9)then your done with opening the ports now to check them
10)http://www.yougetsignal.com/tools/open-ports/ then make sure you have the program you want to use the port then put the port number you put in before and test and hopefully it should be open
GOOD LUCK!!!!!!!!
how to open ports on bt router but please dont blame me if it doesnt work because thats just bt routers some of them work with opening ports and others dont btw if you where wondering why i opened minecraft it was because something needs to be using the port for it to show up as open.