Forecasting Stock Market data on Matlab nntool

Hello,

I am new here and I have developed and trained a neural network by implementing NNTOOL. I have a daily return data for 24 years and I would like to use the first 12 years to fit the model and the remaining 12 years for out of sample forecasting. The aim is to compare out-of-sample forecasting with real return and see how neural network models are accurate.

After running NNtool, how can I make the forecasting and see the performance of different NN models ?

Thank you in advance.