I am working part time how much do u thank I should withheld from my paycheck ?

Not enough info. How old are you? Are you a student? Are you married or single? Do you have any children? How much are you being paid per hour and how many hours do you work? The more allowances you claim, the less tax they withhold. If you aren't working very many hours they won't withhold anything because you don't make enough to hit the withholding tables.