I have installed 2.2006.39-14 2006os and downloaded n770_initfs_flasher.tgz to ~/MyDocs But I can not extract it. Could someone help me?

1. Can I save the Downloaded n770_initfs_flasher.tgz in /home/user or /MyDocs directory? If not, which directory would you recommand?
2. How to extract the file? I tried: tar xvzf n770_initfs_flasher.tgz but can not get it to work.
3. How to make it excutable?
4. How to run the script?
5. Do I need to become root in order to execute above steps?
Thanks.