How do I know what type of law attorney to look for?

I work for a publicly traded company. They claimed that I broke a policy that I was unaware of & had no idea that I broke the policy & no documentation was shown to me to show what I did, I was terminated. I used the companies open door policy to speak to my store manager about an issue with another manager. The retaliation started after that with the store manager a day later paged me to come to his office overhead rudely & abruptly in which everyone including customer could hear that they were going to have some sort of discipline action going to happen which the confidentiality was erased by the page. After my termination there were employees that were talking about the exact information that was on my termination document in which these hourly employees don't have qualified privilege & was shared by the manager I notified the issue to the store manager. employees in the store have commented on the termination stating that I was a thief and must have been stealing the entire time