how do i download the photoshop plugin?
RealWord products are able to use image filters created for Adobe® Photoshop® and compatible software. These filters are produced by various sofware authors and we do not guarantee that each filter will work as expected. Learn how to configure the application to use external image filters.
There are currently 5 verified filters: [1-5]
Once you install and configure the plug-ins to use, the filters appear in application menu or toolbars and you may use them to filter the entire image or the selected rectangle.
The filter names, descriptions, and icons may be customized and you may explicitly pick which fiters should be visible and where.

A height map is being converted to a bumpmap using an external Photoshop®-compatible image filter created by NVIDIA.
External filters are currently usable with RealWorld Icon Editor 2010.1, RealWorld Photos 2008.1 and RealWorld Paint.COM 2009.1.
how do i download the photoshop plugin?
dunno
Try going to the Adobe Photoshop site and look for plugins, or just use a search engine (eg Google) to search for "photoshop plugin".
how do i get downloads to work with real world graphics.
try googling
free | freeware | opensource 8bf | 8bi | ps | photoshop plugins
http://images.google.com/images?q=free | freeware | opensource 8bf | 8bi | ps | photoshop plugins
http://images.google.com/images?q=free | freeware | opensource fractal -"Genuine Fractals" 8bf | 8bi | ps | photoshop plugins
http://www.google.com/search?q=Sinedots 8bf | 8bi plugins
maybe interesting but OT:
http://www.google.com/search?q=+3d +generative |+math 8bf | 8bi plugins freeware | open-source
this looks weak:
http://images.google.com/images?q=+free | +freeware | +open-source +Quaternion +8bf | +8bi | +ps | +photoshop +plugins
and.. i just direct rwpaint to irfanview plugins folder, per link on this page http://www.rw-designer.com/configure-psfilters. Using only one location for apps to grab filters and plugins is efficient...
can't seem to get the lighting effects filter to work. any suggestions?
If you are talking about the original Photoshop filter, there may be problems. Possibly with Photoshop EULA, but also with compatibility. Later versions are using some specialties only available in Photoshop itself - it may work with a much earlier version of the filter - like from 5.0.
Just tested my own plug-ins at www.vanderlee.com. All plug-ins (both the freeware and commercial ones) work fine with RealWorld Paint.COM, making RWPaint probably the best free graphics editor compatible with my plug-ins and the top of my recommendation list.