CSS is a powerful styling language used in conjunction with HTML. There are two main ways of using CSS, one is in the same HTML document as the code is written on, and the other is to create a separate document which only includes the CSS code. The main benefit of this second option (writing a separate CSS document) is that the code you use for one HTML document can be reused for other pages or for an entire site.
Here is how to create a separate CSS document:
We start by opening a new HTML document in Dreamweaver. This can be done either from the Welcome window or form the File menu.

Once you have a HTML document open, go to the CSS panel and choose NEW from the panel menu on the top right corner.

After you select NEW enter the name of your first CSS rule, and select New Style Sheet Document from the menu on the bottom of this window.

All that’s left now is to name your CSS document and save it. Make sure you save the CSS document to the same folder that now contains the first HTML document, and will contain your entire site in the future. The CSS document should be in the root folder and not in its own sub folder.

Easy to follow steps for newbie. Thanks for sharing.
Always happy to hear from you, and happy you like it.
Huh?
How about this one:
1. File > New
2. From the list of “Page Type” (second column from the left) select CSS.
3. Done.
The title of the post was misleading, it has now been fixed. Thanks for your comment.