As an example If the radio code is 1234, you have radio preset buttons on front panel of radio, using button number 1, ensuring that the display shows 0000, press button 1 till first digit reads 1 and then press button 2 till it reads 2 and then press button 3 till it reads 3 and same for button 4, depending on which model radio you have fitted to your K12 micra will depend on next stage but after you have entered the radio code into the unit the display will show your code, either press volume up or tune station up or press and hold the TA button, display will either show CODE OK or will default to WAIT 10 which is wait 10 mins till you can try another code.