Unpacking a tarball through the command line is a simple a matter of memorization. Here is the command to unpack a .tgz or .tar.gz file:
tar -xzf
To unpack tar.bz2 files, simply change the z to a j:
tar -xjf
Upon running one of these commands you should see an extracted version of the directory without the .tar.gz or .tgz extension.