Click on Formulas tab in the top Menu bar select Financial from Function Library section and double-click on PMT. The interest rate here is 3 per year but because the payments are biweekly you need to divide the 3 by 26 the number of biweekly payments made per year. The second argument specifies the payment number.
Nper - The total number of payments.
Using the function PMTrateNPERPV PMT5123012180000 the result is a monthly payment not including insurance and taxes of 96628. If you need to apply it to the entire row you can drag the AutoFill Handle to the far right. For the provided screenshot the formula is -PMT B6B8B9B50. The PMT function below calculates the monthly payment.