if you are talking about “guitar Mass” type songs, i.e. Contemporary Christian praise and worship music, your parish should have a license with CCL (the number should be printed on your songsheets) and there is software (SongSelect) that lets them download music, chords and lyrics. ask your music director or pastor, or whoever prints the songsheets,.
if you are talking about the usual Catholic hymnals, most contemporary ones are licensed by either CIA or Oregon Catholic Press, you can find out by looking in the hymnals. they have downloadable and printed music, lyrics, chords, and some transcriptions for guitar.
If you are fortunate enough to use the Adoremus hymnal you won’t need guitar chords, but they can give you the relevant chant tones.
[quote=susanto]Does anybody know where to buy the Mass song book that has the chords of the songs?
Or are they also available online in internet?