eshop usps extension

I can't install this extension.

I tried uploading the zip file and it says it can't find a valid xml file.

I tried copying the two files (eshop_uspsshipping.php and eshop_uspsshipping.xml) directly to the tmp folder and I get the following when I click on install.

"Warning
JInstaller: :Install: Can't find Joomla XML setup file.
Error
Path does not have a valid package.
Unable to find install package"

What am I doing wrong?

Hi again Franklin,

I have already supported you via ticket system. Just want to say again here: You should go to EShop -> Plugins -> Shipping to install USPS shipping plugin from there.

Sincerely, Giang