So a pie chart works like this
Say we have 4 things
We have 100 fruit
25 bananas, 25 apples, 10 mangoes, 40 oranges, ok?
What you do is you take each type, see the percentage of the whole, and put it in. Eg. 25 is 25% since25/100 = 1/4 = 25%. Thus the bananas section would take up a quarter or 25% of the circle.
Message me if you still don't understand and I'll do my best to explain.