I can guess at a couple of things:
1. The error is complaining that javaaplication7,BankAccount does not exist but you posted code that called the class javaaplication7.Account
2. The class javaaplication7.Account does not have a method called main(), which is required to start a Java application
I'm curious. Why is this help so urgently needed? Should I be hiding my money inside my mattress? I think I'm starting to panic.
You might be better off not using an IDE (I think you are on NetBeans, from the code posted), but using the command line, if you are a new programmer. You have already had two mistakes noticed; correct them and see what happens thereafter,