RCTgo

  First I would like to thank Brad Purvis for his help.  It didn't work but it made me think.  I noticed that when clicking on the
Billboard in the game that it was looking for C:/Users/Users name/documents/My Pictures...  You notice the three dots after My Pictures.
Windows 10 was looking for another folder.  I reinstalled RCT3 Plantinum and checked what the other folder was as there wasn't any other folder in My Pictures file.  The other folder was named RCT.  I found some billboard pictures and placed them in that folder and when I started the game and clicked on the billboard it came up with a folder with an up arrow and a folder named RCT.  I clicked on the RCT folder and that's where my pictures were.  So the procedure is 1) make sure you have only one My Pictures folder in the Documents folder.  If you do get rid of one of them.  2) If you don't have an RCT folder in your My Pictures folder, highlight My Pictures folder and right click, scroll down to new and click and add new folder and name it RCT using all upper case letters.  Go to where your billboard pictres are and transfer them to that RCT folder either by drag and drop or cut and paste.   I pray that this helps those who had the same problem as I did.  It seems like and awfully simple remedy but it worked for me.  Good luck and If you have any questions please ask.

Retsarge