You are in the section for reporting contributions to a self-employed retirement plan. Ordinary personal contributions are to be entered under Deductions & Credits, not business items.
If you are trying to determine the maximum contribution to a SEP-IRA for a SEP plan established under your business, the contribution limit is different than for an ordinary personal IRA contribution and TurboTax uses the worksheet from Chapter 5 of IRS Pub 560 to determine the amount.
