Here are two simple chant hymns: Regina Caeli and Adoro te Devote. Don’t let the Latin scare you, as these famous hymns can be sung in any language. They are easy to learn, catchy, and have been sung by Catholics throughout the world for centuries.
Regina Caeli – sung by the Gloria Singers in Latin and in English
Adoro te Devote – sung in English
12. With regard to compositions of liturgical music, I make my own the “general rule” that St Pius X formulated in these words: “The more closely a composition for church approaches in its movement, inspiration and savour the Gregorian melodic form, the more sacred and liturgical it becomes; and the more out of harmony it is with that supreme model, the less worthy it is of the temple”. It is not, of course, a question of imitating Gregorian chant but rather of ensuring that new compositions are imbued with the same spirit that inspired and little by little came to shape it. – Saint John Paul II Chirograph for the Centenary of Tra le sollecitudini 2003
What I mean by “sound Catholic” is that the Roman Rite has its own sounds and sights. Just as Eastern Rite Catholics, Jews, Muslims and all religions have various sounds and sights that distinguish their liturgies, so does the Roman Rite have its own treasury of songs and rubrics. In this sense, to “sound Catholic” means to sing from the Roman Rite ritual books and to draw inspiration from the Gregorian melodic form.
Musicians can find all they need to sing for Mass in the Roman Gradual. Revised following the second Vatican Council, this book contains the official music for the Roman rite: a complete set of chants for every Sunday and Feast day. It also contains numerous Mass settings. Add some polyphony and you are all set.
However, the best resource for those just starting out is The Parish Book of Chant.
WARNING: singing chant and polyphony is one of the most rewarding and challenging endeavors you can pursue.
REMINDER: Jesus sang. – Mark 14:26 – Be courageous for Jesus!
Praise God and SING like a CATHOLIC!