How to wire AC AC adaptor to Arduino

im trying to make the energy monitor, and am very confused with how to wire the AC AC adaptor to the board. does anyone have any photos to show the wiring? im following this tutorial;
many thanks for all your help!

If you are using the standard 9V AC/AC adapter then you will probably need a barrel connector to plug the adapter into and then use that to wire to the bread board - the polarity won’t matter at this stage

If you find you are exporting rather than importing energy, swap the two leads over.