I cannot confirm an on-line order
After you have selected your itinerary, the following page asks you to:
1. choose how you want to retrieve the tickets
2. enter your complete contact information
3. tick the general terms of sale box
4. click on the “confirm my order” link

On the following page, you enter a secure area (HTTPS) since you must enter the bank information that is required for the on-line payment.
If you cannot access this secure page (https):
From your place of work:

Check with your network administrator that you are authorised to make on-line payments.
From home:

Check your security settings in the corresponding menu, according to the browser that you use.
Examples:
With Internet Explorer: in the "Tools" tab, select the "internet options" menu then the "security" tab and tick the "default level" box.
With Mozilla Firefox: in the "Tools" tab, select the "options" menu.
In the "advanced" section, check that the "security" options are ticked.