You can leave section 2 blank on your Form W-4P.
Since you or your husband are not working more than one job and you don't have any other income sources, your withholding should be sufficient.
There are W-4 calculators that you can use to determine if your withholdings will be adequate.
You can use this calculator to calculate your W-4 amounts. Click here for W-4 Calculator.
The IRS also has a Tax Withholding Estimator for Form W-4 Tax Withholding Estimator
Click here for "How do I update and print a new W-4?"
Click here for "Video: Guide to the W-4 Tax Form Employee's Withholding Allowance Certificate"
Click here for "Withholding Allowances: Are They Still Used on IRS Form W-4
Click here for Form W2-P.