How to go about implementing this software?

Hi,

Somebody asked me to develop a database software in Java (for free, of course) for a shoes company, and I will like to take it for learning. The software needs to mark daily attendance for employees (less than a thousand employees), including overtime, and how much commodities came in and how much was supplied/sold etc.



It also needs to calculate the monthly profit and loss.



I have thought about using MySQL.

I am thinking about how this will be implemented. The confusions are:

1. Although I haven't yet received the proper requirements, but I am assuming the business must have a website. So there must be something like a membership system, where members get a certain discount. This means the website (which would be using JS for the programming part I assume) has to interact with the software implemented in Java. How will this be done? I am just not clear how this kinda thing happens.

2. The employees will mark their attendance on different systems. This means that the data entered in one instance of the database (that is the software operating on one system) needs to be integrated with that in another instance of the database. Now I do know that this is the definition of a database, but can somebody give me a surface idea of how this happens.

I have about a month (can give it a few hours each day only) to prepare for this. So I know that I need to read and practice ERD, Normalization, and JDBC. But I don't know what else.

So can somebody give me a surface idea of how this will be built, and suggest some reading or something? How should I go about this?

Thank you.