My dad is nigerian but acquired a british passport because he was a qualified person working for a british railway firm in the 50's before nigeria got her independence then nigeria was under the british colony. He also met and got married 2 my mum who is portuguerse but I was born in nigeria and had never travelled abroad till I was 25, now I have problems getting a permanent right of residence. Im I a british citizen by descendant or what chapters in the law can I get more information about getting a permanent residency

Have your dad report your birth to the British Embassy in Nigeria...

Edward,
The route you need to look at is the Law of Legacy. See the UKBA website for further details, I can see no reason why you would not be eligible.
Regards x