moving form to a new server/webhost

[webspawner]

When I try tar -cvzf sitebackup.tar.gz .

it tars all file/folders into a folder called ./htdocs/contents

I need to just extract to /contents *** (as the new host has a public_html not htdocs)

So if i opened the new tar'd file I would just see the contents.

When im in htdocs and i try tar -cvzf sitebackuphtdocs.tar.gz

i get
tar: Cowardly refusing to create an empty archive

What is the command for this because when I try tar -cvzf sitebackup.tar.gz full/path/to/folder/htdocs

when i open the archive i get full/path/to/folder/htdocs/contents**

and when im in the htdocs and do tar -cvzf sitebackup.tar.gz