Please help me clean up my code C# Program

I have this

WriteLine("For a loan of the amount of {0:F2}", l.LoanAmount + " , monthly payment is {0:F2}", l.GetMonthlyPayment()); but it wont print the monthly payments. It only shows 0:F2. Also how can I add a comma since its in the thousands?? I want 55000 to be $55,000.00 and monthly payment should show $1,009.69