Basically you have to pour from the highest point. For the skimmer that is normally the pump basket. For the returns it would probably be from a pipe at the filter. Personally I just blow the water out of the lines and plug the returns and skimmer real well so water won't leak back over the winter. Filling my return pipes would take a lot of anti-freeze. I'll blow the lines with a shop-vac and put the caps on while under the slight shop-vac pressure. I then hook a special fixture I made to the appropriate pipe where the shop-vac was connected and pressurize the returns to about 15 psi or so to make sure nothing leaks. The skimmer line only goes to around 6-8 psi for the leak test as the pump basket is pressurized too and the lid could blow off. That run for me is short so I do fill that with AF.
Hope this helps.
Al