Could anyone help me with this question? I don't really know how to approach it.

An instructor's laser pointer produces a beam of light with a circular cross section of diameter 0.600 mm and an average power ' output of 2.50 mW. The beam size stays nearly constant when the instructor uses the laser pointer in the classroom. What is the amplitude E0 of the electric eld of the laser's light? What is the amplitude Bo of the magnetic eld of the laser's light? What is the average energy density uave of the laser's light