The actual "wafer" is the Body of Christ. Holy communion
signifies the universal reception of the Body of Christ by the
entire Catholic community and becoming "one holy community" through
the Body of Christ.
You have to be baptized before you can partake the
communion.
What is the first holy communion?
It is the First time you receive Holy Communion. You need to be
of proper age, be baptised, and know all the facts of Holy
Communion (Such as the real presence of Christ) to receivel
presence of Christ though.