How to move my fridge for easier cleaning?
On some refrigerators the casters are adjustable up and down. 

There is what looks like a bolt head or the top of a screw that you can turn with the appropriate tool that will raise or lower the casters. You may or may not have to remove the grill at the bottom of the fridge that covers the casters to access them.

Whether or not yours has this option,  Emptying the fridge will help greatly in allowing it to move better.