You navigate through linux file system using cd command which means "change directory". You can use ls command to print the files and sub-directories of any directory or use ll command to check their permission and modified time as well.
The root directory in the Linux file system is denoted by a single forward slash (/). It is the top-most directory in the hierarchy of the file system and acts as the starting point for all other directories and files. Everything on a Linux system, including all mounted filesystems, starts from the root directory.