need to make a power supply

hi ok i need to make a power supply needs to be 12v 50watts what would the best way to be get the 50 watt what components are needed im kind of confused on calculating as its my first project some pointers in the right direction would be a great help thanks

For starters, you need a transformer that is capable of about 1.5*50W.

what else would be involved just want to make sure im not missing the point

Depends on:
Input Voltage?
AC, 50/60Hz or DC?
Regulation? (Steady load or intermittent load)?
Ripple?
Size?
Cost?
Efficiency?
RFI suppression?

and about twenty other things I have forgotten...