How do i add extra money to be withheld from federal taxes?

Greetings, @lisaherman.

You can set up to add both Federal and State additional amounts that withheld on the employee's paycheck. Let me guide you on how to do it.

 Here's how:

1. In the left tab, select Workers.
2. Choose Employees.
3. Double-click your employee's name.
4. Click Pay pencil-icon.
5. Select What are Texas's withholdings? pencil-icon.
6. Scroll-down to state taxes.
7. Enter the amount on the Additional amount tab. 
8. Click Done. 

Once done, you can review the employee's paycheck to ensure the state withholding an additional amount calculated accurately.

Also, I've added this article to see information about the new changes to the Federal W-4 and how to enter and print a W-4 for employees: What’s changing with the Federal W-4?.

Know that you're always welcome to post if you have other concerns. Wishing you and your business continued success.