Hi everyone, I have finally managed to sort it out! I am not very good with technical stuff, but with a little help, I finally did it. I got into my router by doing as suggested. My model number is CD3101D R36, but the reason I could not get it to work is because I was also unsure of the IP address I should be using. I knew the routers IP, but it said I could not use that one. The one I finally realised I had to put in was my own computers internal IP, and then choose the numbers I wanted to use to open the ports, and add the program.
Somebody gave me a couple of links. One was port forwarding .com, which is where I bought the program that configures the router for me, but obviously I have to put in the correct ports and IP etc. I have used this program for years and it's always worked great for me and it has great support too.
The other link they gave me was this one.
http://www.canyouseeme.org/
which checks if the ports are open, when you have put them into your router. (very handy)
Once I had put in the correct IP and the 2 ports I wanted to use, it finally showed the ports were open! Thank you everybody for all the help, I would never have done it without you
regards, Linda