In order for me to address your concerns, could you please be more specific. May I know what's going on with your employee's tax withholdings? If you can provide an example, situation or screenshot would be much appreciated.
If you'd like to set up your employee's withholdings, you can see the steps in this article: Form W4 overview.
In the meantime, you can check these articles that can help you with any tax withholding concerns.