If you are self-employed, you would claim that expense under Business Expenses (see the screenshot). It doesn't matter too much which category you choose as long as you don't deduct this expense twice, but it would be clearest if you entered it under Other Miscellaneous Expenses, where you can type in the description and add the amount (see screenshot).

If you are a W-2 employee, you would add the expense as an Employment Expense, under Job-Related Expenses. In the interview for this section, you will come across a screen where you can type in a description and amount.