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, if bank or credit card information was stored I would worry though. A lot. :)
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.
If you are not happy with your password being sent unencrypted then you are out of luck. : (
NB: Do not use a password on this site that you also use for bank web sites.