Can I get fired for giving a guest opinion on a local newspaper?

My article has nothing to do with the job I'm doing or my employer. But yet some employees are not happy to see my name in the newspaper and are forcing the manager to write me up. The manager got mad because i publish something (that is related to where I'm from) without her permission. I don't get it. I did not talk about her or her job or her employees. Why are they mad? As a Permanent Resident, don't I have the right to share my opinion in the newspaper regarding something that concerns me (I responded to false report made by the newspaper about my country of origin and tell the real story)?She says she can fire me fort that. I know that's BS. Before I report her to labor I want some opinions.

Don't wait any longer for an opinion. This sounds like a case of discrimination to me,especially if you didn't disclose anything about your job or anyone,including your boss. There's something called"free speech"in this country and people need to challenge authority when they abuse their power. Like someone else said, holler"Wrongful termination lawsuit"and he or she will probably think twice before throwing their weight around.

There is an old saying "in order to avoid criticism, say nothing, do nothing, and be nothing."

Every time you put something into print, someone is going to get angry. If someone threatens your job, just say "wrongfull termination lawsuit." It worked for me.

In the US some companies have as part of the employment package a requirement that some releases to the media be cleared in advance. I'd talk to the Labor relations board and HR.

It sounds like they are discriminating against you, but if you are under contract it may prohibit it.~

In American common law the doctrine of "Employment At Will" is paramount. You can quit your job at any time and your employer can fire you at any time.
This is the law of the land.
There are a number of exceptions to this -- your employer can't fire you for discriminatory reasons (because you're black, female, Jewish, gay, or disabled). He can't fire you if you have an employment contract and haven't violated the contract.
Other than these few exceptions, -- yes, they can fire you.