Use the plugin manager to install the "QGIS Model Baker" plugin.
The Model Baker Functionalities
After the installation you can find all the Features in the Database > Model Baker menu.
Import / Export Wizard
The wizard contains all the functionalities to create database schemas from INTERLIS models, import / export transferdata and generate QGIS projects from the database. It leads you through the process with all the possiblities you have with the single dialogs. Find a guide through the import and generate process with the wizard and through the export process with the wizard in this documentation.
The Data Validator provides you the possiblity to check the data currently open in your QGIS against an INTERLIS model. You can open the validator panel as well over View > Panels > Model Baker Data Validator. See for more information about it Validate Data
The dataset manager provides you the possiblity to create and rename datasets and generate the baskets for the datasets. More information you can find in the Dataset and Basket Handling
The Model Baker Toolbar
Most of the functionalities are available in the toolbar as well.
The dropdown box there is used to work with the datasets during digitizing / editing data. See for more information the Dataset and Basket Handling