The question is what direction do you want to go? If you go with a cms you will have to succumb to its rules. If you use Dreamweaver you will have to hand code to make it all work.
It appears you are using Dreamweaver, and if you are using the WYSIWYG editor, there should be an option to adjust picture size. Instead of using width=xxx, using width=100% or some other percentage. This will allow the page stretch with the table.
As you mentioned tables are on their way out. To my knowledge, no program will code CSS properly. So, either learn the gap in your knowledge, use a CMS or get a friend that can fix the problems.