I have edited your pic to help with the assembly process.
first things first. Remove the lock cylinder from the switch. put the key in, rotate it to the left, insert a paperclip into the hole releasing the lock, turn further to the left and it will pull out attached to the key. putting the switch in a vise will help this process.
Ok, now for assembly.
Piece #1 is the ignition switch, place the spacer (#2) over the switch, the big end mates with the dash. hold the switch and spacer up on the backside of the dash with one hand, and then screw on the bezel (#3).
at this point all you need to do is tighten the bezel, and reinstall the lock cylinder. also, it usually helps to connect the switch to the harness before you mount to the dash, but not necessary.
hope that is clear enough.
