This video explains what the heck these "spectra" are, and shows you how to solve the most common problem type associated with these, where you're given the energy levels of an atom (usually hydrogen) and then are asked the frequency or energy of a photon which would excite an electron to jump from one level to another.
Rydberg's equation allows you to calculate the energy of each of the orbitals of a hydrogen atom. Not enthralling stuff, no doubt, but you can use it to calculate the absorption and emission spectra of atoms, if you're into that.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)