If you want to look at some more words around this problem you want to look at MVP and MVC. (These stand for Model View Controller and Model View Presenter). Some people will shoot me down for saying this but they are quite similar in concept.
The aim of MVP and MVC is to allow you to design your application logic without even having to think about your application apperance. It also allows you to define your user interactions without implementing an actual GUI. Esentially your model is your application logic, your data, your classes which actually do stuff like talk to your database. Your presenter or controller is what interacts with your model and what controls your user interface and reacts to user operations on the interface. Finally your View is your winforms design or your web page.
I'm sure you will be able to find plenty of material on the web about this but to give you some concrete help with this problem should serve to inform and illustrate your reading.
The first thing you need to do is start creating your objects that represent your data. So you will have a CaseNote object which is contains the casenote data. You will have a case note data container of some sort such as a case note database. You can define the logical operations and properties of these as if they where real items.
Then you would move on to define your presenter or controller which will define the operations that you want to support from the GUI. At the same time you should define an Interface that will define for the presenter/controller what operations is can perform on the GUI. So for instance your presenter may expose a method called SearchForCaseNote which takes a string parameter. Your view Interface will expose a method called DisplayCaseNote. When a user clicks on the search button the view will pass through the command to the presenter which will then call the model to get the data. The presenter may format the data at this point, i.e. convert DateTime object to a string and then pass the data back to the view through the interface define method called DisplayCaseNote.
You don't have to use the View interface, you could call into the view directly, but having the interface means you can have many different view implementations.
One last thing i need to mention is where you create these different parts of your application. My view is everything thing should fall out from the presenter/controller. So when you application starts it creates the presenter/controller object which then create and displays your view passing itself as a variable to the view. The presenter/controller can then either create the initial models by loading them from disk or ideally discover them through a dependency injection container like unity. In fact using unity to discover the view implementation is probably a better idea again as it gives you true seperation between view and presenter/controller. When you come to move to another view, (i.e. open another window), your presenter/controller should expose a method such as DisplayDetailPage which the view calls when a button is clicked. This would create the presenter/controller for the next view which would in turn create the view and get a reference to the model.
Hope this helps.