Any page using a form to submit data is considered these days insecure when this data is not transfered over a secure connection (i.e. https).
In order to have a secure connection in place, you need a certificate given out by a secure authority.
Of course you can buy this certificate, or acquire a free of charge certificate. Unfortunatly these expire quickly, i.e. with 3 months. Renewing these certificates is not something you want to do manually.