PHP has no typical "gui" like Dreamweaver does for HTML. PHP is a coding language, and one that doesn't have a GUI like C# or .NET applications.
Zend Studio is proprietary software, meaning that Zend created and sells the product for a profit. It is however, worth every penny if you're really developing PHP applications.
The Eclipse plug-in called PDT (the PHP for Eclipse project) does not have a design page. There is good reason: there are no "controls" or anything to design. PHP is all back-end coding. It's all text-based. The design view of Dreamweaver is only for HTML. It's a WYSIWYG (What you see is what you get) editor, and only useful for HTML and XHTML documents. The only difference between design view and your browser is that in Dreamweaver, you're afforded the ability to move and add "elements" with a few clicks and put them where you need, rather than having to hard-code it.
For a beginner like you I'd say use a small text program like E-Texteditor or EditPlus or Notepad++ or even just notepad. They all do the same thing (create text-based files and highlight based on syntax). The advantage to using these over dreamweaver is overhead. Dreamweaver can be a resource hog. Although, Dreamweaver offers code-hints I believe. But even that can be added to things like EditPlus through user tools. Or what's better is to just use the manual as you go.
I've been doing this for about 5 years now, and I use a mix between Edit Plus, E-Texteditor, Zend Studio 5.5, and NuSphere PhpED. But the resource I use the most: www.php.net <-- The first place to look when you're stuck, chances are someone has noted it