The first thing you need to do if you want to write HTML 5 with Dreamweaver CS5 is make sure that you have the 11.0.3 update. Go to the “Help” menu and choose “Updates...”. This will open a new application — the Adobe Application manager. Click on Dreamweaver and if that update is listed you will need to install it and then restart your computer.
Once you have the 11.0.3 update, you will have access to a bunch of new features including support for HTML 5 and CSS 3.
