Download module here.
1. unzip it. put blockuseronline directory module in prestashop\modules.
2. go to your admin panel. (www.myshop.com/adminxxx)
3. On main menu choose Modules -> Modules
4. All modules will appear.
5. On left side menu, choose other modules (on the bottom).
6. Install block user online modules then visitor counter widget will appear in your front page
This is sample image of the result:
Bayu Prawira