can i make counters, such as scores, life points, health,etc. How? And how do i have it be added to or subtracted from?
This can be achieved by making a use of variables. Check out the AGS Beginner's FAQ (http://www.rain-day.com/harbinger/faq/)
Example:
// main global script
int score = 0;
int life_points = 10;
int health = 100;
to add or substract:
score = score + 5; // will add 5 to score
health = health - 10; // will subtract 10 from health
Yes, please do check the BFAQ.