I am trying to build a simple multi layer perceptron Neural Network in Java, but apparently my calculations are off. I am looking for a beginner-level tutorial which can help me to understand how to properly calculate forward and backward pass, preferably with examples.
Apart the mentioned resources, this also might be of help: MLP Java example. It's from the University of Sydney and includes theory and a Java implementation.
You can follow this tutorial Neural Network: A Complete Beginners Guide from Scratch. It's covered the very basics and also shared the code.