Click on Federal Taxes, then Deductions & Credits, then scroll down
toward the bottom of the page (you may have to click "Skip to see all tax
breaks" to display the various deductions) and click on Employment Expenses.
Then select Job Expenses For W-2 Income. You'll advance thru several screens where TurboTax will show you a various expenses and ask if any apply to you. Then you'll come to a page that says Job-Related Expenses, with a write-in grid for description & amount.
This is where you'll write in Professional Dues and the amount you paid.
Then continue to the end of the section and hit Done.