Of what. There is area and perimeter for all 2-D objects.
Lets say L= Length, W= Width, H= Height, S=side, and B=base. Also, lets say A= Area.
Perimeter is just adding up all side lengths.
A of rectangle: L*W
A of triangle: 1/2*(B*H)
A of trapezoid: 1/2*H*(top B+Bottom B)
Those are just some of the basic ones you will need to know, among others.
This might also help:
http://en.wikipedia.org/wiki/Area