There is not a place to tell TurboTax that you worked for a Non-Profit as working for a non-profit does not generally make your income not taxable. The non-profit organization does not have to pay taxes on the income they receive, however, the people working for them and receiving a pay check do have to pay taxes on the income that the organization pays them.
Did you get a W2 for it? You don't need to report it was at a non profit. You don't get a deduction for working for a non-profit. That doesn't need to go on your tax return.
There is not a place to tell TurboTax that you worked for a Non-Profit as working for a non-profit does not generally make your income not taxable. The non-profit organization does not have to pay taxes on the income they receive, however, the people working for them and receiving a pay check do have to pay taxes on the income that the organization pays them.