There are several types of surveys to do.
The daily surveys (you can complete one for a given site once each 24 hours) can be found in the Daily section of the Offers. There are several different sites to choose from -- I like Give Us Your 2 cents best.
If you do complete a survey, leave the "congrads" window open and check your account page to confirm that it has credited before you close it. Might take 10 minutes to credit (if it doesn't credit, there's a problem with communications between the survey company and FC. Happens, but not that often) You will frequently be DQ'd (disqualified) for a survey because you fail to meet the demographics wanted. Don't dismay, just keep trying until you do qualify or they run out of surveys.
Then there are the "surveys" that are really offers. I don't do those, but you will find then in the offers pages.
You access all of these on the FC site via the Offers link. The only thing that is sent to you is the Daily paid email. You sign up for that in the Daily section of Offers.