how to make this model, please also attach the formula of excel, thank you!

Mortgage Pool CFs (w/ service fee) 1000 mortgages \begin{tabular}{l|l} $250,000 & =PMT(.08/12,360,250000,0,0) \\ 30 -year, fixed & =$1,834.41 \end{tabular} 8% interest 0.5% service fee WAC=7.5% - WAM=30 years - 7.5% is "passed through" to investors