Pascal VOC 2012 dataset prediction

Hello everyone,
I am trying to build FCN-32 model using pytorch on pascal voc 2012 dataset. My output from FCN-32 is H x W x num_classes. How should I visualize my prediction ?

Where are the classification labels in the dataset?? There are 5k images but I could only find 500 labels. Where are these labels stored in the original file structure?