First, Train up your ANN network using input, output. When, the training is complete, you may find a variable (object) generally named 'net'. Save this variable for further use. To predict new output, use this variable. For further information, please try "Neural Network Toolbox User's Guide - MathWorks".
You may also use some regression modeling algorithms for modeling your data and predict given another data. You can also perform a comparison between ANN and regression analysis based on the accuracy of each method.
Regression analysis such as multiple linear regression, generalized additive models, etc.