You picked up some of those great big bags from your local home improvement store, but you are having problems getting your leaves and debris into the bag.
You can make a quick and easy "funnel" for using with your bag. Locate an old plastic laundry basket or tall trash can.
Open up your bag and place the basket/can inside the bag to make sure that it fits.
Once you have confirmed this, simply cut off the bottom of the basket/can. Now place back in the bag and start filling.
Once your bag is full, remove your basket/can and place in the next bag for use.