In the Every tick event, add the action Text -> Set text.
Using the & operator, we can convert a number to text and join it to another text string. So for the text, enter:
"Score: " & Score (or the name of your variable)
The first part ("Score: ") means the text will always begin with the phrase Score:. The second part (Score) is the actual value of the Score global variable. The & joins them together in to one piece of text.
Extract from the beginner's guide to C2