You basically need to know three options for tar:

-x EXTRACT -c CREATE -f - USE STDIN/OUT

to create a tar file of the current directory:

tar -cf - . | gzip > /tmp/foo.tar.gz

to extract:

gzip < /tmp/foo.tar.gz | tar -xf -

why tar has all the options was someone's idea they were helping you out -- they weren't

Create is -c --- remember that eXtract is -x - remember that -f - is stdout/stdin depending on your need -- remember that

pipes are your friend.