Turn it around to top view, there you will find a small High Frequency transformer.
The circuit here is a "Switch Mode" power supply essentially build by 3 blocks :
a) Line voltage rectifier and HF switch.
b) HF transformer.
c) low voltage rectifier and regulator.
These circuit types are definately not for newcomers, as they will very easy burn up in smoke by even the smallest mistake.
More so, they can easily take out your house circuit fuse, leaving you in total darkness, on such mistakes.
Besides you WILL get quite a few electric shocks with this circuit, until you have learned your lesson.
lastly : this is the standard type of circuit found in almost any small charger for mobil phones, labtops etc.
There is a huge selction of voltage and amperage versions on ready made units, for a few quid.