I would like to make my own splash screen (not a boot splash). Read the kde manual but it is way advanced for me. Is there a simple program out there that does it?

You could just download some themes from kde-look.org, look at their structure and then copy that. A few years ago, I made my own without using the KDE docs.

Then how do you make all the png that need to go with it? Are all of them necessary?

It is not really that hard go to www.kde-look.org download a splash package anyone will pretty much do, open the file up with Ark or similar take note of the file names/size of the pictures. Now all you have to do is make a directory for your theme making the file names the same as in the file/pictures the same size then modify an existing theme.rc in the package use Ark again to create a file.tar of the working directory viola you have a working splash of course you would open up the theme manager dialog install then test to make sure it is to your liking.

Edit: BTW if you have never noticed all lot of the splash's use the same icons on the bottom just take some of the ones you like best from an existing package for re-use maybe even changing only the large picture above them then you have just a simple substition in an existing package changing only the name(s) in the .rc file.