The user inputs are as follows:
Months1: number of months for the loan period to begin- enter 3 for 3 months
Rate1: enter in decimals. For e.g. 5
Months2: number of months for the loan period to end- enter 6 for 6 months
Rate2: enter in decimals. For e.g. 8
Frequency of spot rates: chosen between Continuous and Loan period
References
John C. Hull, "Options, Futures, and Other Derivatives", 8/E, Prentice Hall, 2012.