Recently, I try to change The name of my country to Kingdom for Empire, but The game say I have to use OpenID. I don't know the man, I asked other players and none of them used it to make changes. What is the problem?
OpenID is a service allowing other websites to verify that you own your nation. It has nothing to do with name changes.
I think you may instead be talking about changing your pre-title from Kingdom to Empire. This can be done on the Settings page. Below 500 million population you can select a pre-title from the listed options provided there. When your nation is over 500 million population you can type in any pre-title you wish (as long as it abides by the rules, so no bad language please).
Ballotonia
"Een volk dat voor tirannen zwicht zal meer dan lijf en goed verliezen, dan dooft het licht…" -- H.M. van Randwijk