Is there any way to change the title menu to your own personal design?

What do you mean "title menu," Santa? You mean the intro blurb "You have been chosen to lead your people to victory blah blah" or do you mean the like background art that comes up when you go to your mod?

For main menu in a mod folder create the assets folder then art folder in that then interface folder in that then main menu folder in that then put your main menu image there in dds format, and give it the same name as the main menu in the standard games assets folder.