Hi and welcome.
Hope this helps.
"Switch on the radio, code appears in display.
Press either tuning button to select the first digit of the code then press preset 1 button to store the first digit in the unit memory.
Use the same procedure for the 2nd, 3rd and 4th code numbers.
If correct code has been entered then a double beep will sound and you can listen to your cassettes.
If you muck it up then it'll say wait in the display and you have to leave the unit on, 2 mins for the first time then 4 then 8 then 16 until you lose the will to live and go to halfords for a new radio!!
Post some pictures of your car.
We like pictures.