Hey i just got fired today and i want to sue because i felt discrmnation what should i do .plz answer need hel?

hey i just got fired from my job today and i was there for a month and a week i had great customer service and a wonderful attuide i was the only african american and i got wrote up 3 time in a month yea i know sound insane...first wrote up was because no call or no show when i called in and let them no.....and the second one was because they said i wasnt going on my breaks when i had to ...and if i was late for a break it was because i had customers in my line and i will ring them up irst...they told me not to do that and turn off my lite and send them to somebody else line i told them if i did that it would not be wonderful customer services they said they dont care...then i had a ccustomer call in and complaint about i was playing with my cell phone in my draw and had her waiteing 4 10 mins she called in 2 times when my cell phone was in my locker and i found out it was one of the workers who called in and said that ...then the 3rd one was because they said i clock back in from lunch and set back down and start eating again and they said one of the workers went back and check my punch and i was not right and they also said i was binding up paper and trying to get it or discount ..when i wasnt i was returning them back to the shelf and puting them in there place ...also i had customers call in and said the love my services and they also went to the counter and said that they think i was the best they had work there..also i was a worker who worked there and people had called and complain about her and also they didnt give her a write up or anything and she had bad customer services every complain i had was by a couple of workers