For Windows Vista or later, all you need to do is connect your Xperia to your PC with a suitable USB cable (micro USB plug at the phone end, standard USB plug at the other end).
When the autoplay box appears on your PC, choose "Open device to view files".
You should then see two folders as below:
a) Internal storage
b) SD card
Double-click whichever of the two contains your camera pictures, then double-click the 'Pictures' folder.