When I log in I get a security warning that the password is being sent in an insecure manner

This means that the password you are sending is being sent unencrypted.

This site uses basic HTTP security , not HTTPS or SSL security used by banks.

Basically the web browser is warning you that I am not using top "bank grade" level security. I would not worry about this for sticker information.

As I do not store bank details or credit card details directly on this site the higher level of encryption is not needed, and so it is not enforced.

NB: Do not use a password on this site that you also use for bank web sites.