I can not find how to get the canister apart to empty the dirt.

From the bottom of your machine going upwards past the handle that is on the canister portion of this vacuum, you will see that the top of that canister had a depression where you should be able to put your fingers in, and gently pull that lid back, opening the vacuum bag compartment. According to the manual, simply pull that back, exposing the bag. To remove the bag, pull the cardboard plate on the top of the bag, out towards the no open face. Throw away your old bag, and take your new bag, fold down the paper sides of the bag, then slide the new bag into the track completely. Close your lid, and you are done.
While you have this compartment open, it's a good idea to check your filter that sits below the paper bag.

Part numbers
Paper Bag: SC-P11
Filter: SC-F2

I hope this helps you.