Welcome! This project is made to help a collab called Mario Kart 7, which can be found at https://scratch.mit.edu/studios/31537204 I guess you started this project to create some tracks: open it and read the information to understand how to!
The places where it is written (Placeholder) means a track preview or cup art needs to go in that place. Credit to @-CreativeCatTest for the main code and the original project, Nintendo for the music and Mario Kart 7 and myself for spending 2 hours just having to change things!