To check what directory you're working in you have to type in PWD command and hit enter.
This will output the full path of the directory you are in.
If you want to change your directory you have to type in cd (which stands for Change Directory) and type in the destination you want to go to. e.g. cd Desktop/
If you want to go back by one, you type in cd .. and this will take you back by one directory.
That's it, I hope you found this helpful