To add web UI to your existing application right click on the Application name on the Project tree and select Add New....

Under CDP select Add Web UI and click at Choose....

If your existing application is a console application, just follow the steps in the wizard. If your existing application is a GUI application, choose 'Create New' in the wizard. After thes wizard is finished, Design mode becomes enabled, and you can start creating your GUI as described in Design mode manual. It is possible to have several Web UI applications.

Once the GUI is ready and you want to run it in web browser, do the following:

When the application is running and connected, click on the application in Configure mode Project tree and choose the Table Editor tab. Go to the Properties section, find the property called WebURL. This is the link for the web browser. You can also open the browser directly by clicking the icon next to the url. Note that there is a WebFilesToServe property in the application configuration that must list all files and folders that should be accessible in the web browser. If the WebFilesToServe is not set up correctly, then the web browser might not show the content correctly, or it might not function correctly.