I wouldn't recommend to propose the Online version on a web site, because only users under IE / Windows will be able to run it. The other web browsers don't support plug-ins anymore, including the Java plug-in which is required for Sweet Home 3D Online.

If you just want to display and navigate in 3D homes designed with Sweet Home 3D, you may propose Sweet Home 3D JS Viewer on your web server (see also here). This viewer is programmed in JavaScript / WebGL and will run under most browsers / operating systems.