One (simple) way is to edit FORMSWEB.CFG file; see ColorScheme parameter. Its values can be changed to Teal, Titanium, Red, Khaki, Blue, Olive, or Purple. It is, though, ignored if lookAndFeel is set to Generic.
If that's not what you are looking for, you could create your own visual attributes (in the Forms Builder) and use them when appropriate.
I'm astonished as well. How come you didn't realize that it was weekend when some/many/most Forum members spend their free time with their friends, families, hobbies etc. and NOT answering your questions?
Besides, if you are in a hurry, call Oracle Support (or any other Oracle consultant) (which will not be free of charge). Furthermore, there are plenty resources available for researching. I'd suggest Oracle Technology Network Forms Forum. Use its Search feature and enjoy reading what people have said, done and whether they succeeded or not.