How to unpack a tar file on Ubuntu?

I'm trying to install java on Ubuntu (I'm new to it) and I'm getting no luck on the terminal. I tried using synaptic but that didn't work either. Any idea on how to install this onto my desktop? It would be helpful (I'm unfamiliar with terminal except for when I've jail broken my iphone).

If you know how to open up a console or the command line, the command is tar xvf your.tar

Open the Software Center and in the search box type in Java. When you find the Java you want ti install click on it and choose install. It does this automatically. There's no reason to be using terminal commands in Linux unless the repository file system does not have what you need. When you opened Synaptic, did you click reload and when it get done checking the repositories and updates the list, click mark all updates and install theses. If you didn't update this, synaptic only list what is already installed and nothing else. You can use update manager to bring the Linux up to date and current. You will also want to toye in the search box Ubuntu Restricted and install these because this installs the propritery hadrware and software files that Ubuntu can't install by default because they are copyright protected. There are several different versions of Java in Linux. If you just did a terminal command that just said Java it doesn't know what to install.