That's not what you want.

You want a 220 volt-primary, 14-volt secondary transformer with its primary connected to the mains through a fuse.

In the illustration, you can omit the transistor and capacitor, as there's already AC at the input. You then need a bridge rectifier at the secondary, and a filter cap, probably with a small-value resistor between the bridge and the capacitor, and then a voltage regulator of your choice and voltage, on the output side. If you consult the datasheet for nearly any simple 78xxx voltage regulator, there will be application examples. You should read and understand the voltage regulator datasheet, the bridge rectified spec's, and the transformer spec's.

A typical wall-wart has a transformer, rectifier, and capacitor, and often a thermal interruptor. That's done the difficult work for you. Of course you'll need the datasheet for the wall-wart.

None of this is rocket science, though I wouldn't allow an unsupervised 10-year old attempt it. A 12-year-old should be able to manage it, though.

RE