Some of my cousins and friends have tested at 23andme or familytreeDNA, due to my urging, and now they are asking me what to do next. I dedicate this post to them.
Autosomal DNA testing will not not magically find your ancestors. You will need to work at it and may have very little success if not enough of your known and unknown relatives have tested. It will give you many clues and hints about where your ancestors were from. Be sure to use some of the admix tools at GEDmatch.com on your results if that interests you, see my post on GEDmatch.
I suggest that if you are not familiar with DNA or DNA testing that you read my DNA basics page and if you have tested at 23andme also read my post on 23andme basics.
Assuming that you all do not want to spend the kind of time on this that I do (an hour or two most days for the last year); here is how to get the most for the least time input.
First you need to understand that an autosomal DNA test is nowhere near as definitive as a Y chromosome test, it can show you that you are related because you share runs of identical SNPs (referred to as segment matches from here on) with someone but not exactly how or even how close. After the 2nd cousin level the amount you will share with a relative gets more and more random. I have a few 9th cousins I share a one segment match with who like me have extensive trees and that is the closest match we have found. ISOGG has published the expected ranges of cMs and number of segments on their wiki that relatives share at different levels of relationship.
So what was your objective taking the DNA test? If it was just to satisfy your curiosity then my post on 23andme basics should answer your questions. If finding new relatives is of interest then read on.