I kept the two tickets we got from France in 2012 and looked at them to help answer this question. If they still use the same white forms highlighted with green, at the top is Avis de Contravention au Code de la Route. On the right hand side in a box labeled Vitesse is the limit (Limitée à) and how fast you were going (Enregistrée à). You can run anything else by Google Translate to get the gist of what happened.
On the back under Avertissement is a caption that says Pour payer l'amende, vous avez le choix... The first bullet under that is Par Internet with an address (www.amendes.gouv.fr) where you can pay using your Visa or MasterCard. I was concerned about Google translating when I went to that website, but it automatically popped up in English. You may have to click on the language.
I had to put in the No d'Avis de Contravention (speeding ticket number) for each ticket. That is printed on the Carte de Paiement (payment card) at the bottom of the page which is intended for people mailing in their payment. When I paid, I got a Fine Payment Proof to print as a receipt. That was all in English. The speeding ticket number appears as the E-payment no: at the top of the receipt, so it is easy to be sure you are paying the right fine.
Our tickets also were for 45 EUR each. According to the tickets, we went 112 km/h in a 90 km/h zone on the A75 somewhat south of Clermont-Ferrand heading toward Montpellier and 100 km/h in a 90 km/h zone on the RN100 between Remoulins and Avignon. That information was in a box on the left side of the form labeled Lieu de l'Infraction.
You do need to pay the fines and just chalk it up to experience. We add the cost of any tickets to the cost of car rental. See the recent link on the topic of tickets already cited in a response above.
Be sure to tell your credit card company you are going to be charging something in France before you pay, or your CC might be rejected because they think it is a fraudulent charge.