replacing a png in theme?

I've been looking at some of the theming tutorials, but there not getting me past step one. If all I want to do is copy an existing theme, replace a few png's, and use that new theme while preserving the old one what are the steps involved? Every time I try and do it, reaper loads what looks like an old 1.x theme with nothing I've done showing up. Am I wrong in thinking that the white tie sticky on getting started theming is a little dated? Anyway, I'm still scanning through the tutorials, but if anyone knows of a tutorial on this subject specifically (or could come in here) it would be most appreciated.

It seems your copied theme can't find the folder with the images (and rtconfig file). Prefs->Appearance->Theme Editor Tick "Theme uses image resources" and choose the right folder. Hit Apply and save the theme. Now, just for checking, open the saved ReaperTheme file with notepad and scroll down to the bottom, there you will find this: [REAPER] ui_img=XYZ The ui_img name should now match with the resources folder name.

Thanks. This worked.