Repair broken battery cover
Does anyone know how to place all these pieces
back into the cover
I don't think you can put these parts back together to make this work. It appears you are missing the screws and it also looks like the plastic is damaged.
Basically you need a new battery door assembly. Olympus Corp has spun off its camera division as they have stopped making cameras. You'll need to contact them see if they can ship you the replacement assembly. I'll warn you they are very possessive with their manilas and parts. They will try to get you to ship the camera to them for repair and it won't be cheap!
Play the heart strings as best as you can, I've managed to get a battery case from them with tears running down my face to break their will ;-}
You might want to look locally for a repair shop they may have the part, or look at finding a parts system.