Plz Help Me I am struggling!

Question

I am new to programming and also .NET ..I have to do a project "Inventory Control and Accounting " system .. And I have to follow some guide lines also..
1. I have to design common classes- This mean I have to create classes to create ,add ,delete ,update data for the database. Data validation classes..
2.The Database Design..

So I am struggled with the first part designing common classes..
I am using c#.NET .

Can I get some sample code reels for those ..I am using MySql as my database..

Cheers
Groovy