Check out this page on making paper beams.
How Bridges Work (How Stuff Works) (p. 1-7 are most useful).
This guy gives a brief lecture on truss Bridges.
You will need to design and build a paper bridge using as many pieces of paper as you like. Paper glue is allowed. You will also be able to use basic tape such as masking tape or Scotch tape. Tape should be used to hold things together, but should not be covering every surface.