get all the ripped papers
The hatch (Dragon Face lock) that accesses the museum is up the broken board ladder just before the Docks exit. Once you have all the Dragon Face pieces, you can open the hatch at night to enter the museum. (see related question)
First, you have to find all the pieces of paper around counterfeit island. When the pictures are assembled together, it will show a picture of a dragon. Make sure the dragon on the door is the same as the dragon in the picture.
The "ram thing" is a dragon face. (see the related question)
You see it as the board ladder near the end of the Underground Tour. It is a locked hatch up into the museum's supply room. To open it at night, solve the dragon face puzzle. (see related question)
If you mean the hatch thing on the roof in the middle you have to collect all 6 pieces of torn paper to form a picture of the dragon lock mechanism. Adjust the mechanism so it matches the picture and it will let you in.
You have to find all the pieces of the picture, so that you can open the secret entrance in the underground tunnel.
That should NOT be possible. In order to have the 6 pieces to the Dragon Face picture, you had to open the door to the Supply Room. And you cannot open the dragon face without all 6 pieces.
The art museum on counterfeit island opens after you go to the guy at the dock.
When you leave the museum, it is night. Take the picture to the underground tunnel (you have to go through the Docks because Downtown is closed). Climb the wooden ladder to reach the dragon lock. Arrange the features to match the picture, then press the latch bar at the top. The hatch will open and you enter the museum's Supply Room.
First, you have to collect all 5 pieces of the dragon drawing. Then, rearrange the locks features to match the drawing.
Locations of the Dragon Face pieces: The City Docks : top of the boat mast The City Docks : in the sand to the far right The Museum : on top of the museum The Museum : in the Supply Room The Inn : above the street artist, near the roof The Underground : in the arch where the bulb is hanging You open the Dragon Face hatch in the Underground at night, by matching the lock features to the picture.
You don't. It is just a distraction.