To create a web portal, you will need way more than Dreamweaver and "SQL".
Let's look at the details:
1) First of all, you need to know HTML extremely well (you can use Dreamweaver here, but don't rely on its WYSIWYG functionality).
2) For styling you need to be quite good with CSS. This is no easy task, especially if you want to make your portal cross browser compatible.
4) You need some server side technology. Here you can choose between the most common ones, which would include ASP, JSP, PHP (and maybe ROR - Ruby on Rails).
5) If you need to save information in a database, you need to understand SQL commands. You can choose your flavor from the most popular ones (MySQL, MS SQL, PostgreSQL)
6) Last but not least, you should know something about the webserver you are using (Apache, IIS). This is not too critical, but the more you know the better...
I guess that's pretty much it. :)
I have been working in web development for many years and I just now have written my first portal. It is an extremely complex area of web development and it is tough to do right.
Of course there are always the open source portal projects like Joomla or PHPNuke (see link below). But even those need some of the above knowledge for insallation and customization.