See the following FAQ for instructions to change to itemized deductions.
How do I change from the standard deduction to itemized (or vice-versa)?
However, if your itemized deductions are the same as your standard deduction, I suggest that you stick with the standard deduction, unless you are filing as married filing separately and your spouse is using itemized deductions. Your tax will be the same either way, but if you use the itemized deductions the IRS could challenge any of your deductions. They can't challenge the standard deduction.
