Expenses you paid for a karate class are not deductible on a tax return.
If you made contributions to a 401(k), those will already be entered on your W-2, Box 12 Code D. They are not entered anywhere else on your tax return.
Have you filed yet?
The class is not deductible. The 401K comes out of your paychecks and you only enter it from the W2 box 12, nowhere else. It has already been deducted from the wages in box 1 and you can't deduct it again.