How does one interconvert wavelength, frequency, and energy of electromagnetic radiation?

Frequency is the number of vibrations per second that the wave    goes through.

For an       electromagnetic wave, the idea of amplitude is difficult. We draw waves, looking like   sine curves, and then show  bigger amplitude as being taller ( and deeper ) peaks     ( and troughs). Which is   fine for water waves  and sound waves but not for light.... there is no "taller" or "deeper" for light waves. Increased  amplitude for light means more photons per second arriving..... not "bigger" photons - just more of them.

You know that the energy of a photon depends ONLY on its frequency ( which is really freaky when you think about it. )

E = h . f

and then you can use the wave equation ( v = f ? )  to get  E = h . c / ?

and thats about it. Very simple , sort of, but not at all easy to understand.