Figure out your exemptions. State taxes, like federal taxes, are dependent upon how many dependents you have and whether or not you are married. Count up the number of dependents, or children, you have, and add yourself and your spouse to the number. This is your total exemptions.
Obtain a copy of your state's withholding tables. You can find them on the state's department of revenue website. If you don't have Internet access at your home, you can get to the website by going to your public library and using the computers there. If you cannot access a computer, contact your state's department of revenue or tax office and request one be mailed to you, ask your employer to provide a copy or see if the library has the latest version.
Find the section based on how you are paid. The withholding tables are typically broken down by weekly, biweekly, semimonthly or monthly pay.
Find your marriage status. Within your pay frequency, some states break down your filing status into single, married and head of household.
Look through the tables for your gross pay. These are listed as a range of funds. Go across the table to the correct column. The columns are based on the number of dependents. The number in the correct column, across from the correct pay range, is your withholding amount.