Make sure that the Nuxeo JSF UI target package is checked in your project's Application Definition to get all the needed features in Nuxeo Studio.
Defining a new search form basically consists in defining a new content view that is flagged as a Search content view.
To set a new search form that will replace the Default search form displayed when you click on the Search tab:
- In Studio, click on the Listings & Views > Search menu item.
- Click on the Create button to create a new default search.
- Configure the base query, the form and the results table, like you would on any other content view (see How to Define a New Content View).
- Save and deploy.