does anyone know how I can add my own layout on freewebs.com
instead of using one of there templates?

yeah... when you sign up select html mode and that should let you input your html template

they changed the layout a bit so if you still have trouble, and if your using the advance features (like you make your own site instead of templates from freewebs) when you log-in theres a build&edit page, if you haven't added a page click on the to add your html