The commands given below make up only a very small portion of the total available. Each command has none or many, many options to satisfy anybody's taste. Among other things, it is this incredible richness which has many serious UNIX users stick with commands to be typed rather then switch over to graphical interfaces with buttons to click on.
You frequently will see the phrase "..]$" in this write-up. This is what we call the command prompt which appears whenever a particular command or program has executed. It basically tells you that the computer is done with the previous task and is waiting for you to type in another command. The details of this prompt depend in first instance on your system administrator but you can change it as well which is somewhat messy to do though.
If you are brandnew to the UNIX world I recommend you read up about the different commands in the order they are listed below and doing the examples presented for each command as you go along.