fixed income interest rate risk management tutorial

can someone plz recommend a good book or site that explains how to use value at risk and other measures to measure and manage the interest rate risk of fixed income portfolios. preferably something with actual examples where i cna see how to calculate value at risk using monte carlo simulations and historical methods. and examples of calculating durations and convexity. i see a lot of material on this online and in books but its just so complex for me, i need a gentle introduction with basic examples. any suggestions? thx