Recently I made a Responsible Disclosure for 2 security vulnerabilities in Prestashop Module Send to a Friend and provided also the fixes for them in a Github Pull Request. This was done in coordination with Prestashop Core Team to ensure the issue was not public until Prestashop owners of Online Stores have the time to update the module and also to guarantee that the code for the fixes was according to their rules.
This Tutorial is a detailed How To aimed for Prestashop beginners, therefore I will not expected, from you, any knowledge at all about Prestasho Admin Interface. Step by Step to Update a Module in Prestashop Version 1.6.* During this Prestashop Tutorial the Url used to reach the Prestashop Back Office will be prestashop-tutorials.dev/v1616/secret-admin-folder and your one should be your-domain.com/your-secret-admin-folder or if your store is not in the root folder then it should be like your-domain.com/online-store-folder/your-secret-admin-folder.