first you must decompress the .tar file out of the .tgz this is done
> gzip -d archive.tgz
The -d swich means that you want to decompress the file instead of compressing it. If you read your directory now (with "ls -l"on UNIX or "dir" on DOS) you will find a file named archive.tar instead of the archive.tgz file. Note that archive.tar has a greater size than the former archive.tgz now that it is decompressed. To get a list of contents from a tar archive you can type tar -tf archive.tar.
Second you must extract the contents from the .tar archive. Simply
> tar -xvf archive.tar
The switches mean -x for eXtract, -v for Verbose and -f for file. The -f switch is there for historical reasons.
The extracted contents are now in your current working directory. It may be either a new subdirectory or a bunch
of new files. It is always a good idea to view the list of contents with tar -tf archive.tar before extracting so you know
what is going to happen. The archive.tar file will not get deleted by tar -xvf
You can also use the program untgz.exe. Just type
untgz archive.tgz and it works ;-)