With all due respect I strictly disagree with much of the above.
Yes, archives of these forums contain nearly endless amount of knowledge. This particular question had been discussed at least 3 times in last couple of years.
I am sure it is more recent than that. Remember all those polls...
But amount of data accessible through search function is overwhelming and most importantly not always relevant! There are tons of threads that are either too complicated for beginner or are simply wrong or misleading.
That is true for everything in the world. That's where you, as a person, come in. You filter the crap out and get the big picture. Uninvolved cherry-picking leads to dogmatic approach to the game which is less fun and not so effective on harder settings. EDIT: Also, wrong threads are the result of non-systematic approach. That's what makes forums harder to use. Easy way to recognize better threads is simply by reading the comments and valuing the opinion by number of posts and date joined (how I did that). Not perfect, but it works.
I was lurking in these forum for months searching for knowledge that would help me beat low lvl game, instead of just ask and move on much faster.
These forums are very friendly both for pros and noobs.
Anyway, I would recommend
http://www.civfanatics.com/civ4/strategy/introductory_courses. Especially
Commonly Used Acronyms in the Civ Community and
Sisiutil's Strategy Guide for Beginners.