The Tardis can be summoned with a Tardis key, which can be obtained with a Kontron crystal. These crystals are very rare in caves, but they can also be found in dungeon chests or chests you get from breaking lucky blocks.
tardisInside
Once summoned, you must right click the door of the Tardis, which will teleport you inside of it. You are now in the Tardis Dimension. The Tardis has an entire infinite dimension for you to build in. You can use the Tardis to fly around and even change dimensions. To get started, find the Sonic Screwdriver on the console in the middle of the room.
Right-Click the Screwdriver to pick it up. Then, move to the back of the Console where you will find a new spot to put the Screwdriver. Insert the Screwdriver and select Library. You can then take the Screwdriver out once more and shift right-click until the sonic screwdriver turns yellow. You can then make your library in one of three places. Right click one of the blocks and your library will appear.
From here on out, the library will tell you pretty much anything you need to know about the Tardis mod. For any extra help, visit the Tardis FANDOM.