Assuming you are speaking of your login page... Your images are not using an SSl source. The are correctly coded relatively, but the shared SSL is not configured or your Zen Cart is not configured correctly to use it as the source for the credit card image for example is

http://www.monpetitsinge.com/include...ges/paypal.gif

Instead of

https://cx89.justhost.com/~monpeti1/...ges/paypal.gif

~Melanie