Lots of different furnaces have been sold over the years so I can't possibly show a picture of all possible variations. What I try to do is provide some examples that will help you identify the parts of your furnace. All furnaces have more or less the same parts, they just get arranged differently. Click on any of the images to see a larger version. Note that on the larger images, your browser will probably resize the image to fit your screen. If you click on it again you will be able to see the full detail.
You will always need to know the model number before you can buy the right parts! It is also very helpful to have the part number.
Another example of the model label. You can also see information about size (75,000 BTU), and that it was set for natural gas when it left the factory.
I removed the cover plate so you can see the limit switches and the transformer. The parts on your furnace are probably in different places, but will look much the same.
In this picture you are looking at the side of a fan/blower unit. The surface that is down in this picture would be mounted to the back of the furnace.