AC has far more booking classes to Europe than seating classes and FF mile earning is extremely complex, made even worse by location-specific earning.

You can go to aircanada.com and input your AC locator (under Manage Your Bookings) to get your booking class. Then read the archaic FF mile earning rules on either Aeroplan.com or the sticky in this forum.
Sorry, realized the sticky's not there anymore. You can do a search on "Aeroplan Mileage" on this forum.

Unless you're Aeroplan Prestige/Elite/Super Elite, AC does not open up the preferred economy seats. This was the cause of the demise of free E+ seating on UA.