If you have booked standard flight tickets, you can upgrade to a higher class on Air France. Here are the steps for an Air France seat upgrade:

• Visit the official website of Air France. 
• Head to the "Manage Bookings" section. 
• Plug in the booking reference number and your last name. 
• From the list, choose your flight to make an upgrade. 
• Click on the "Upgrade button" to upgrade through card or miles. 
• After the seat has been upgraded, you will receive confirmation by mail. 

If you need more assistance you can contact Air France Customer Service and you can also read the blog by Airlines Group Travel at the given link for information.