Replacing the bag is pretty straightforward. Simply follow five below steps:  • First: remove the dirt canister from the unit  • Second: rotate the cardboard header, pull down the adapter of the bag. You can now take the used bag out and discard it.  • Third: install the new bag by folding it over the top and aligning the slots on the bag collar with the tabs. • Fourth: be sure to push the bag collar firmly onto the adapter.  • Fifth: Lift the dirt canister to the unit's base and engage the latches back in. I would recommend you to double-check it to make sure that the canister sits firmly to the gasket. This short how-to video will give you a better illustration: