What I would recommend is that you get your package working with a simple design and then just add the rest of the features and refinements one by one, testing all along the way.
Do not try to implement everything in one go - trying to track down what is going wrong will be too difficult.
Very best of luck.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.