If you are a recent college graduate, and are starting your new job, please read on....
Your employer has to deduct income taxes from your paycheck. The amount to deduct assumes your salary will be paid throughout the year.
But since you've just started your job and aren't working all year, too much tax will be withheld. You'll get a nice refund when filing income taxes next year, but if getting a larger paycheck now is more important, ask your employer to withhold less tax, so your paycheck is larger now.
To do that, your employer will use a "part time tax withholding table", provided by IRS.
Hope this helps. Please let us know if you have any questions.