Could someone help me.I am only a beginner (Rookie 
) and I need help in this invention that I am Inventing.Could someone tell how could I do this.When I click a button or send a power signal to my Arduino It would ligth up a Lcd screen and say a message.
Thanks
James
And once that thread has scared you away because it's so long and talks about unrelated examples, have a look at these pages:
Your task is to combine those two examples.
I haven't watched these, but they may be helpful also:
I'm not saying that original link is bad, as in you should try to read it if you can (please do!). But I'm saying these other pages might be a bit more interesting considering what you've told us you want to do.
If one learns to tackle their projects methodically, the sooner they will become proficient (if of course that's important) 
.