If you haven't had a chance to look around, I recommend perusing, you will find many interesting and useful topics. Also there are many knowledgable folks here who can help if you have questions.
tyco05 was pointing out, that we have some guidelines for users to follow. It is worth you while to go through and re-read the rules of the forum.
The main one here, is that you need to show some work before we can assist you. If you don't know where to begin. For starters, try and state what you understand about the problem and where you are getting stuck. You might outline, what does your question mean going from 4.0p to 4.0s transition for sodium and what are you trying to find the wavelengh of.