The metal nameplate information is usually found in one of the places shown.
A) Along the bottom panel; left, right or anywhere in-between.
B) Inside the fridge or freezer section, near the bottom. You may have to remove a crisper drawer to see it.
C) Remove the kickplate and look along the condenser air openings.
D) Somewhere on the back of the refrigerator, usually very high or very low, or possibly on any wiring diagram that may be pasted to the back of the refrigerator.
E) If you absolutely cannot find a metal nameplate, some refrigerators have a paper sales sticker left on, just inside the door. This will be an incomplete model number, but it is better than nothing and it should be good enough to get most parts with.
If all else fails, check the original papers that came with your fridge when it was new. They should contain the model number SOMEWHERE.