Transform a CDs charger into MP3

HELLO EVERYONE.
My query is to see if anyone knows how an original CDs can be transformed so that MP3 can also read.
My car is a 2001 Ibiza Stella with original CDs charger.
I have advanced knowledge of mechanics and I have seen online some cables that are coupled to the charger to cancel it and transform it into a USB output, I have an MP3 player of those who plug in the lighter and emit the signal on the radio, and I had thought about disassembling it to attach it to the CD charger, but I do not know how to do it so that the buttons are then operated and send the information to the screen.
I await your help