Okay, so you've read the previous piece on Gregorian Chant, and you're chompin' at the bit to infiltrate your parish with what Vatican II intended all along...
Remember one thing: this doesn't happen overnight. Expect to spend as much as a year in collaboration with others, before even setting foot inside the parish church with the likes of this. In some ways, singing in unison is a greater challenge than singing in harmony, as many voices must synchronize as one voice. Not as easy as it sounds.
And another thing: if you're not going to do it right, don't do it at all. I've had a part in such efforts that were half-baked from the get-go, usually because the pastor's "full support" was little more than lip service, as well as the misperception that a casually celebrated Mass in the vernacular can persist in remaining casual with the introduction of plainchant.
In the meantime, you'll want a primer on reading and singing Gregorian chant. Our friends Arlene and Jeffrey have come to the rescue again, with an earlier piece from Crisis magazine entitled "An Idiot's Guide to Square Notes." Download that sucker and give it a good read.
While you're doing that, you will have already ordered your educational material in the mail. The late Doctor Theodore Marier devoted his life to the preservation of Gregorian Chant in the post-conciliar era, before it was the post-baby-boomer-type-kewl thing to do. With the collaboration of the good Sisters at the Abbey of Regina Laudis near Bethlehem, Connecticut, an excellent tutorial with recorded disc has been produced. "A Gregorian Chant Master Class" is available to order from their website.