Download the file and unzip it to an empty folder on your hard drive.
If you already have the NopCommerce USPS shipping plugin installed, follow these directions. If you have not installed it, or have uninstalled it from your site, then follow the normal instructions for installing a new NopCommerce plugin. You can find our instructions for installing new plugins in the forum on our web site. http://www.effective-systems.net/boards
1. Copy the Nop.Plugin.Shipping.USPS.dll file from the zip file and paste it into the /Plugins/Shipping.USPS folder on your web site. (replacing the file that was there)
2. Log onto your site as an administrator and go to the site administration and click on “restart application” in the upper right hand corner.