To use the central server component, you need to have a computer with WordPress installed that will be reachable from mobile devices. You can either:
You'll also need to make sure you have the Woo Commerce plugin installed and a list of products entered.
You can get the plugin here. Keep track of where you store the downloaded files because WordPress will ask you for them.
Open the WordPress administration screen and choose 'Plugins' from the navigation, then choose one of the 'Add New' buttons.
Next click the 'Upload Plugin' button. A small form will expand out.
Click the 'Choose File' button and use the choose file dialog box to indicate the location of the .zip file downloaded a couple steps ago. After selecting the file, click the 'Install Now' button.
The only thing left is to click the 'Activate Plugin' button. Once activated, a new top-level menu item will appear.