where to show expenses for a non-profit convention where I was an officer and delegate

Yes, you can claim a deduction for expenses you incurred to attend a convention of a charitable organization as a delegate or officer. It's considered performing services for the organization. For details see "Out-of-Pocket Expenses in Giving Services" on page 5 of IRS Publication 526.

You enter the expenses in TurboTax as a contribution to the charity. Contributions to charity are an itemized deduction. It will not make any difference in your tax unless your total itemized deductions are more than your standard deduction.