Tar files creation command :

tar -cvf mystuff.tar mystuff/
tar -czvf mystuff.tgz mystuff/

extracting:

tar -xvf mystuff.tar
tar -xzvf mystuff.tgz
testing/viewing:

tar -tvf mystuff.tar
tar -tzvf mystuff.tgz

Note : .tgz is the same thing as .tar.gz