Neural Network

I am writing a code that will classify 10 characters given 8 features using a Neural Network. I have the forward part working already and in need of help doing the back propagation part. I can't wrap my head around coding it. My code stops to the part where it just calculates the outer layers change for the weights (delta)

Need:
- Be able to train by epoch and by pattern
- Plot error over iterations
- After training, classify characters and use the coded function to make a confusion matrix