First try to display the text to the console, then you know that it at least reads a line from a external file. Then try to display the text in the canvas, and be sure that the position, size and colour are correct. If this still not works, then it's possible that the text will be display correctly, but then the fireworks animation overwrites the text. And therefore, it isn't visible.

was thinking that...is there a way to have it being displayed while the animation is running?

Erase the background. Display the text. Display the fireworks. Repeat on each frame (that's what draw() does, anyway).