I am a Beginner in java and I need help desparately. I have a project that I have been assigned and it is to biuld a functionality to process a credit card batch payment. I have done most of the work, now it's time to do the implementation and I don't know where to begin. I already have my use cases and the sequence diagram, but I can't seem to get started on biulding the classes, etc. Could you please show me how to get started?