To endorse the check, you'll just have to flip it over and sign the line with the x to the left of it. This line will be found at the top of the check, and you'll sign it sideways. Do this right before you go to the ATM or the bank, so that your check cannot be cashed if you lose it. If you don't endorse the check, that makes it harder for the bank to accept it from a person who wants to cash it for ulterior motives.
FDIC insured means that the government will give you your money back (up to $100,000) in case your bank goes out of business and can't pay you. If you have more than $100,000 to put into savings, try spreading it out over several FDIC banks with no more than $100,000 in each account.
Updated March 31, 2017. Definition: The FDIC is the Federal Deposit Insurance Corporation. It is an independent agency of the Federal government. The U.S. Congress does not appropriate funds. Instead, it is funded by premiums from banks. It also earns interest on its investments in U.S. Treasury bonds.