I assume you're teaching an RCIA
class. Thank you for committing yourself
to teaching the faith to inquirers!
Briefly, the process goes as follows.
First, you need a cause. This
is when a group of the faithful
decided they want to advocate
the canonization of a holy individual
who has died. They ask the local
bishop; if he approves, the person
is called "Servant of God
Information about the persons
writing, works, and life is collected.
This is forwarded to the Congregation
of the Causes of the Saints, and
the next step of canonization
is sought: "Venerable So-and-So".
Once a saint is venerable, people
start seeking his or her intercession,
because for non-martyrs a miracle
is required for the next step,
beatification ("Blessed So-and-So").
The miracle must be a medical
miracle, it must be wrought only
through that saint's intercession,
it must be immediate, and it must
rule out any natural cause or
explanation. A panel of doctors,
both Catholic and non-Catholic,
and theologians is consulted,
who cross-examine the recipient
of the miracle. Meanwhile the
person's life and works continue
to be examined.
If everything continues to check
out with no obstacles, and if
there is a second miracle (only
one miracle is required for martyrs),
the person is canonized. A canonization
is a declaration (customarily
regarded as infallible, although
this has never been formally defined) that
the person is in heaven. Note
that a canonization doesn't put
someone in heaven; it merely recognizes
that they are already there. Canonizations
have followed this process only
since around the twelfth century.