How to tell if I have been subject to gender discrimination in hiring practices?

Gaming Controller Position - Indian Casino. The job posting had a few requirements that I did not meet so I didn't apply for it. However, I mentioned the job to my boss, VP of Finance. He tells me it would be to stressful and looking for someone with a CPA or CIA requirement. I have been indirectly and directly under my boss for six years. Recently, he hired a girl with less qualification than I had. I forgot to mention we are both tribal members. I am full-blooded and the hired person is half white. My title is Project Accountant. The girl is an Auditor from Gaming Compliance. He purposely hired this girl and overlooked me. Why I dont know! She's never managed anyone. My boss didn't hire according to the job requirements. He could have promoted me within instead of going to the outside of the casino. We get along fine! I have proven myself at this casino and capable of handling multiple complex task. I have succeeded in all projects assigned to me. I'm disgusted and will not speak to my boss unless it's business. Is there anything I can do? I was looked over for a promotion and raise. Right now, I'm looking for a job and will continue to do so until I get away from my boss.