To untar that stuff run the command "tar zxvf ~/newvps.tgz". That will extract the information in the tar file to the current directory you are in with the full path (versus "tar zcvf ~/newvps.tgz" which created the tar/gzip). So if you're in /tmp you would end up with directories like:
/tmp/vz/private/<vpsid>/<vps filesystem>
/tmp/etc/sysconfig/vz-scripts/<vpsid>.conf
and would run the command (with the VPS stopped):
# This is to back up the base VPS created by the vzcreate command on the new machine
# changing the name from <vpsid> to <vpsid>-orig (i.e. 100 becomes 100-orig):
mv /vz/private/<vpsid> /vz/private/<vpsid>-orig
# This backs up the conf file in the same way:
mv /etc/sysconfig/vz-scripts/<vpsid>.conf /etc/sysconfig/vz-scripts/<vpsid>-orig.conf
# This moves the VPS data into the proper place:
mv /tmp/vz/private/<vpsid> /vz/private/
# This puts the configuration file back in place:
mv /tmp/etc/sysconfig/vz-scripts/<vpsid>.conf /etc/sysconfig/vz-scripts/<vpsid>.conf
Also, check out There is a lot of awesome flags that can be used with it to make your administrative life easier.