If you want to integrate WONDER with and existing Application, you must follow all the steps described in the integration page of the WONDER wiki. Note that it's not just adding the frameworks to the project, you really have to make all the code changes described there (it's easy to do, but don't skip it, or you'll have problems).
- Right-click on your application project icon, and choose "Properties" from the contextual menu.
- Choose "Java Build Path" from the list on the left.
- Click on the "ProjectsLibraries" tab on the right.
- Click the "Add ...Library" button, select "WebObjects Frameworks", click "Next" and choose your framework. Click "OK" to close the projects Build Path window.
- Click "OK" to close the project properties window.
- Done. Now you're project is linking with your framework. If you think this is overkill, think again when you need to do a maintenance application of a backoffice. You'll love the time you spent separating the model code from the application. Also, this helps you write better code, because model code shouldn't need to know anything about the presentation layer. If you try to do that in your framework, you'll get an error, so you really can't do it!
If you don't want to create the model framework now, at least take the advice of keeping the model layer fully independent from the presentation layer. This will make it easier if you decide, in the future, to separate the model code to a framework as described here.