Chevrolet 2008 Optra Owner's Manual page 50

If you need to install more than one child restraint in the
rear seat, be sure to read Where to Put the Restraint
on page 1-36.
1. Put the child restraint on the seat.
2. Pick up the latch plate, and run the lap and shoulder
portions of the vehicle's safety belt through or
around the restraint. The child restraint instructions
will show you how.
3. Push the latch plate into the buckle until it clicks.
If you find that the latch plate will not go fully into
the buckle, see if you are using the correct buckle.
1-46
Make sure the release button is positioned so you
would be able to unbuckle the safety belt quickly
if necessary.
4. Pull the rest of the shoulder belt all the way out of
the retractor to set the lock.