In this module, you can study how to find the surface area of a cube, a cuboid (or rectangular prism) and a triangular prism.
The above video shows a teacher explaining how to find the surface area of a rectangular prism.
 
The video above is a visual explanation about how people figured out the formulas for the surface area of rectangular and triangular prisms and cylinders.
 
The surface area formulae for all prisms and cylinders are the same. They are all (two x the area of the base) plus (the perimeter of the base x the height of the object).
Even though a prism is a three-dimensional object, its surface area is two-dimensional.
Use these search terms to find additional resources:
surface area of cube
surface area of cuboid
surface area of rectangular prism
surface area of triangular prism