1. Download the zip file for appropriate version

aftership-prestashop-14x.zip (for 1.4.x)
aftership-prestashop-15x.zip (for 1.5.x)
aftership-prestashop-16x.zip (for 1.6.x)

2. Login to your PrestaShop Admin Panel and Select "Modules and Services"


Click "Add a new module"


Click "Choose a file"


Select the file from your system


Click "Upload this module"


Click on "Install"


Click "Procced with Installation"


After this you will see a message "Module installed successfully"