Seeing the inside of your piano is fairly easy. With a grand piano, just stand at the right side of the piano and lift the top, or lid up and you will see a stick that tilts up and fits in a spot under the lid. This holds the lid up. (Some lids are quite heavy.) Now grab the thing the music sits on and slide it toward you. It should slide right out. Some pianos have a funny way this comes off, such as Knabe's, in which case you slide it in and out lifting gently until it hits a slot and it lifts off. Now you can see just about everything.
Some verticals are tricky to open. Don't try to open an Everrett piano. I'm sure every tuner remembers the first time they tried to open an Everrett. If you have a smaller, modern piano feel under the left side of the lid. If there are hinges on the left side don't go any further. Most vertical lids are hinged in the back and just lift right up in front and can be rested on the wall. Some lids have a left and right clip holding the lid down and might need a firm impact from the base of the palm to open. The front panel often comes off with a latch on the left and right inside corners. If there are screws, better stop here. The vertical panel under the keybed simply falls right out once the little metal stop screwed to the underside of the keyboard is pressed up. Don't try this if there are fancy parts above the pedals or an assembly holding the pedals in front of the panel.
Be warned, I take no responsibility for what you do, or what you might find inside!