convert a home cell phone charger to usb data/charger for computer?

what wires to what wires?

Go to pinouts.ru. You'll have to know a little about power supplies or take it to someone who does.
110100101108 years ago
to make phone - computer data cable see here the entry maps of the plugs and wire each to its same one in the usb to make phone charge cable (do only if the phone needs about 4.9 - 5.2 V) find which wires in the phone charger are + -. link them to + - in the usb cable. dont link any data wires to use the power block (the charger itself) to charge other usb stuff (do only if it outputs between 4.9 - 5 V !) find usb socket and link + - to + - and leave data wires alone