look down the back and you will see a rubber hose in a loop. You can pull it out as long as you do not stretch the hose taught. If you clean the floor, and spray it with WUL+water, or furniture polish or WD40, it will be slippery and the cooker will slide more easily. this really does make a terrific difference, so does cleaning off the sticky dirt.
You may well find that there is a safety-chain holding the back of the cooker to the wall. This is actually required by gas regulations, to prevent it falling over if a child climbs on the open oven door, but is often omitted. With luck the chain will have a sort of dog-lead clip fastening it to a screw-eye in the wall. If not you might have to unscrew it (but buy a clip for next time)