Now we need to install the plugin to be able to import our data, which means we have to go back to our main dashboard. So, go back to your main dashboard (http://multisite.longren.org/wp-admin/), and mouse over the Tools item in the left-hand menu, and then click on the Import item. You'll be at the Import page again. Click on the WordPress link at the end of the Import page, as illustrated in the following screenshot:
Click to install WordPress Importer
After clicking on the WordPress item, a modal window will appear with a big red Install Now button in the top-right corner of the modal window. You can see an illustration of the modal window in the following screenshot. Just click on the Install Now button to install the plugin. It should just install automatically.
Click to REALLY install WordPress Importer
Now, this method may not work for everyone, like me. If you click the red Install Now button and you see a screen like what you see in the following...