1. Build hidden layers using DenseLayer:

new DenseLayer.Builder()
 .nOut(nOut)
 .dist(new NormalDistribution(0.001, 0.005))
 .activation(Activation.RELU)
 .build();

2. Add AddDenseLayer to the layer structure by calling layer():

builder.layer(new DenseLayer.Builder()
 .nOut(500)
 .dist(new NormalDistribution(0.001, 0.005))
 .activation(Activation.RELU)
 .build());