Social Security income is typically not taxed as long as the combined taxable income of an individual or a married couple is below a certain level. IRS publication 915 provides more information on how your social security benefit is taxed. You may benefit from seeking the guidance of a tax advisor if you have further questions.
Regardless of your age, you will need to declare the distribution on the IRS Form 1040 which is your personal tax return. Show the amount of the IRA withdrawal on the line that state IRA distributions. Since you took the withdrawal before you reached age 59½, unless you met one of the exceptions listed in Publication 590-B, you will need to pay an additional 10% tax on early distributions and report it on Form 1040 as an additional tax. You will need to complete and attach a Form 5329 to report any amount subject to the early distribution penalty or to state an exception to a penalty. Certain distributions from Roth IRAs are not taxable.