Dreamweaver will create better sites than the one you have there and it is worth the investment if you are serious about getting into web design. Lots of overlapping and invalid HTML ( see validator: HTML - http://validator.w3.org/ , CSS - http://jigsaw.w3.org/css-validator/ ). As far as learning Dreamweaver, having a working knowledge of HTML and CSS is a good start for many and I would recommend the tutorials at W3Schools for that ( http://www.w3schools.com/ ). As far as Dreamweaver in concerned, there are some very good tutorials on this website that you may want to check out including Adobe TV ( http://tv.adobe.com/ ) and Adobe Devnet ( http://www.adobe.com/devnet/dreamweaver/ ).
If you need help or have any questions about the tutorials most of the community here is fairly knowledgeable and there are some experts around too who know just about all there is to know about Dreamweaver.
I can't say if DW is worth the investment for you or not. That's a decision only you can make.
DW is Pro-level software that can do as little or as much as you require. As SnakEyez02 says, you will need a certain skill-set to get the most out of it. A working knowledge of CSS code, X/HTML markup and web terminology will greatly improve your results with DW.
HTML & CSS Tutorials - http://w3schools.com/
From Tables to CSS Web Design Part 1 -
Creating your first web site in DW CS4 -