How to configure a custom command in a Linux system (Mac book also applies)

I believe that the students who are familiar with Linux have a problem is that if you want to view a file to a level or multilevel to the CD switch directory, which has a convenient way to switch the wood? Just like shortcut keys.
This is the configuration of the custom command in the Linux system, very simple??

In file/ROOT/.BASHRC, add the following line:

Alias mycommand = "Cd/root"

Executing mycommand directly at the terminal will execute Cd/root

?? : source ~/.bash_profile This command must be remembered for execution, and this line of command is to load your modified command in the system

~ This symbol represents your home directory,
. Bash_profile is a hidden file that is primarily used to configure the bash shell,
Source ~/.bash_profile is to make this configuration file effective immediately after modification.

How to configure a custom command in a Linux system (Mac book also applies)