Build you own lab a.k.a. install SQL Server on your home computer then go to Books Online a.k.a. BOL (installed alongside SQL Server) and read the chapter about architecture.
After that, start practicing... practicing... practicing on the example databases.
Read the newbies section of this forum, try to answer questions by yourself and check your candidate answer with what senior guys are saying.
What's your background?
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at Amazon and other bookstores.Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.