Regardless of your age, you will need to declare the distribution on the IRS Form 1040 which is your personal tax return. Record the amount of the IRA withdrawal on line 4a or the line that states “IRA distributions”.
Since you took the withdrawal before you reached age 59½, you will need to pay an additional 10% tax on early distributions and report it on Form 1040 as an additional tax. That is, unless you met one of the exceptions listed in Publication 590-B.
You will need to complete and attach 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.