If you followed my tutorial correctly, you have a text attribute which holds the text to show on screen. The only thing you have to do is center the text using:
Draw [textAttribute] at x [((screenwidth/2) - (get with of text [textAttribute] using current font/2))] and y [textYPosition]
Try to use google more often, you might find it usefull. Also please stop sending me pm's everytime you have a question related to my tutorials. I am active enough to read all questions posted and there are more people then me able to help you like LetMeThink.