How do I prove I was discriminated against at my workplace ?

Let me tell you what happened and then please give your opinion.
I am a security officer at a large telemarketing company. We are required to wear uniforms. Me and one of my co-workers stopped wearing our uniforms during the weekends. OK I get to work Monday and my supervisor calls me to her office and she has a write-up on me for not being in uniform. I sign it and go on. My co-worker who does not were his uniform either was working the same shift as our supervisor (they were in the same office for 8 hours) and he was out of uniform and he did not receive a write up. I have noticed that my supervisor (who is a black female) flirts and acts silly in the presence of two of my co-workers, who are black males. I have one other co-worker and he is white and she talks bad about him behind his back. I can feel her animosity towards me. I am not sure if it is because I am white or because I am a female. What should I do and how can I prove my feelings?

Yes I agree I did violate the policy and I signed my write up and took my punishment. By her not writing us both up she is showing favortism towards the other person I feel because of his race or because she thinks he's cute and can flirt with him.

The circumstances as you relate them would in themselves prove discrimination, go the the Human resources director or if a small company go to the owner and ask for assistance if they refuse consult an attorney.~

You don't have any grounds for a discrimination lawsuit. Sure it is stupid that your coworker did not get reprimanded but you still VIOLATED THE POLICY.

If you don't like getting in trouble for violating policies, than STOP disobeying them!!

Discrimination claims require one of two things:
1. A blatant irrefutable act of discrimination, such as something in writing specifically listing that your race, gender, etc. is the reason for an adverse decision.
2. A systematic practice over an extended period of time.

The fact that you were disciplined while a black, male co-worker was not does not come close to establishing discrimination. There are way too many other variables. If this pattern involved a larger sampling of workers and continued over a period of time you could prove discrimination by pointing to the pattern. Short of being able to show a pattern of abuse, or being able to find something that amounts to an admission, you simply won't be able to prove discrimination.