Many weblogs, manuals, tutorials and websites can help you on the road to replacing table-based designs with css. Iolaire.net started with PVII's plug-ins for Dreamweaver, which help make nice rollover css menus. The 2002 version of iolaire.net featured these menus, but over time Iolaire moved away from Dreamweaver. The reason for this is the high cost of commercial programs compared with open source as well as the difficulty of creating precisely placed items in Dreamweaver. Most of the work on the current site was done first in Apple's free Project Building and then jEdit which became the dominate editor because it is available for both Mac at home and PC use during lunch at work.
Jeffrey Zeldman's The Daily Report is one of the key reads for css design as well as visiting all of the links found at stopdesign. Additionally Eric Meyer at meyerweb.com has written books and articles to help others learn the art. But is funny calling it an art because using css to design standards compliant websites is just as easy as not designing standards compliant websites. It is irksome when companies exclude a browser or an operating system just because few of their customers use them.
On this site the blog header style of meyerweb.com was imitated and the navigational menus came from gazingus.org - Using Lists for DHTML Menus.
Trial and error is the best way to do css design when you are first learning. If you have layout problems backup your css and then start removing lines until the problem is fixed!