SEO versus Joomla/Wordpress/Dreamweaver

Hello, I am trying to develop my first websites/blogs. I'd like to ask to experienced developers, if websites built by means of Joomla and blogs built by means of Wordpress have the best code to perform SEO or if these websites cannot scale google because of poor/bad codes.

I am learning how to use dreamweaver, but meanwhile I wanted to develop something with these two CMSs.

These two CMS are completely different and used for various tasks. You'd better first learned Wordpress. Configure the blog, install plug-ins, then you can change the scripts or write your own. You should focus on something one than trying to learn a lot of things but superficial.