I cannot find so much documentation in JavaFX.
And I will be happy to know how I can do this :
When I type a word in a textarea, fx "google" or "facebook". Can I so do like it can change color of google to fx green, and changes the font and stuff like that.
I will be happy to know how i can do this :).
No. JavaFX 8 does not support multiple colors for text in TextArea.
You could try Tomas Mikula's RichTextFX control and see if that works for you.
The other options are:
Addressing additional coments
TextFlow is a readonly control, not editable like a TextArea is. Creating an feature rich styleable text editor from scratch using only core JavaFX 8 components is a large and complicated task, which I would not advise most people to undertake. Instead, using or contributing to existing JavaFX editor solutions such as RichTextFX or other similar projects which may arise would likely yield better results and a more productive outcome.