Instillation of Pari theme is very easy. Its the same method that you follow for installation of other Drupal 7 themes. This tutorial shows how to install Pari theme on a Drupal 7 website.
Step 1: Download the theme
Download the latest version of Pari theme from project page.
https://www.drupal.org/project/pari
The download file will be a compressed .zip or .tar.gz file
Step 2: Extract the files
Right click the zip file and extract the zip file.
After extracting the zip file you will get a folder named pari-7.x-x.x
Step 3: Open Extracted Folder
Open the extracted folder pari-7.x-x.x. Inside this folder, you will find another folder names pari.
Step 4: Upload the theme folder
Upload this pari folder to sites/all/themes directory of your Drupal installation.
Step 5: Enable the theme
Now go to administer > site building > themes
domain.com/admin/appearance
Click Enable and set default link below the theme.
Step 6: Perform basic theme settings
After you have enabled Pari theme, perform few basic settings from admin/appearance/settings/pari or by clicking Settings link.
Done!!