Roboticus touched on it in his post. The change directory command is cd. However, before I use cd I start with the list command ls. This allows me to see everything in my home directory. From there, I cd into the needed directory. I may alternate these commands two or three times depending upon what level I need to get to. Admittedly, I prefer visual queues. Your stylings may vary
That being said, I'm always starting from my Ubuntu home directory. I would assume this is the case for you as well. But to check this, you can use the working directory command pwd. If you're not at your home directory use the cd command followed by nothing to navigate there.I've found this command line reference helpful.
I still think that you need a '/' at the beginning of the line when you intend to navigate multiple directories on the command line such as when you try to run your newline.pl script.