Installing and upgrading help

You did replace '/path/to/moodle' with *your* Moodle location? If the path was right and you didn't get an error it probably worked. 

Don't worry about the plugins thing. Just get basic Moodle working for now. In fact, don't get too hung up on permissions at this stage. If it works, good. 

However... it's time well spent to understand how Unix/Linux file ownership and permissions work. Also the basics of the chown and chmod commands. It won't take long and will make your life much easier.