Create a tar archive called my-directory.tar of a directory my-directory/ in the current working directory.
You can use this short tar command.
tar -cvf my-directory.tar my-directory/
Or this more verbose tar command.
tar --create --verbose --file my-directory.tar my-directory/
-c or --create tells tar to create a new archivev or --verbosetells tar to produce verbose outputf or --filetells tar that the next parameter will be the tar file to create, extract, append to, list, etc.