Hi mildfoam. This is a lot to take on. What is your experience with web design? Photoshop is not a web design tool, so it's better to start thinking in terms of code editors etc. It's no sall undertaking to build a CMS. It would take years of programming knowhow to do it well. You might be better off looking at something like WordPress and installing a pre-made theme which you can then learn to tinker with.
If you want to learn web design from scratch, check out some of the great SitePoint books that start from the beginning.

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