I have a letter from DFAS (Defense Finance Accounting Service) saying that there's $798 that I can claim as a misc deduction. I can't figure out where to put it?

Miscellaneous deductions go on your Schedule A.  If this is an employee job expense (for instance, uniforms), please follow these instructions to enter your deductible employee job expenses in TurboTax,

• In your open Federal return, choose the Deductions & Credits tab 
• Scroll down to Employment Expenses and Show more    
• Choose Job Expenses for W-2 Income and Start or Revisit