What kind of proof do you need for discrimination lawsuits and how do you proceed?

i work the midnight to eight am shift. for the second time i was told i was going to be a supervisor on night shift and recieve a pay raise. during my 2 month time as a supervisor i did not recieve a pay raise. i recieved minimal training and when a problem arose that i was did not know i called my direct supervisor and he told me what to do. when my manager arrived in the morning he said it was wrong called me a moron and i explained to him this is what my supervisor had told me. that night when i arrived to work i was informed that i was no longer a supervisor by another shifts supervisor. the first time they informed me i was going to be a supervisor i was given the drawer key and told how to write a ticket and an eve shift supervisor told me to figure it out. i was a supervisor for approx 6 months when i was then informed that i was not doing my job correctly et never recieved my raise called a moron and dumb and told that i was no longer a supervisor. both times when another person came to the shift i work 0000-0800 they were given the supervisor postion and i was relieved of my duties as supervisor. i am the only african american employee of the diamond truck wash. i have worked at my job for almost 2 years during this time i have been called a nigger on a regular basis and been the brunt of racist jokes and slurs. i have been called a moron dumb et stupid by my manager several times. i was replaced by a white male and a 1/2 hispanic male as my job as a supervisor. i have been fired once by a day shift supervisor for a family emergency. prior to my getting fired i had called my manager he had told me he would take care of it. and then fired me during my month of unemployment before they called to tell me to come back to work i applied for unemployment and when i talked with the unemployment officer she informed me that my manager had told her i had quit. et did not qualify for unemployment. i need to know how to proceed and if i have a discrimination case?