Try searching the forum on manchester code. There's a transition in the middle of the bit period. Its direction determines 1 or 0.

Code:
   _          _
1=| |_   0=|_|
or vice versa - which is 1 and which is 0 is arbitrary.

There's usually a series of pulses without spaces to denote the start of a code.

However, if the codes use KeeLoq, you'll never see the same code twice so storing for comparison with later codes is a waste of time and effort..