The First step is to get an instrument used for playing Irish music. The most common instrument is the Penny Whistle. The reasonfor this is because the Irish Flute is very easy to play and very cheap. You can buy one for around $7.
Get a method book, this will help you with the notes and it will also give you some Music. To see some Irish Music, Click Here.To see a Fingering Chart, Click Here.
Find other musicians to play with. Find a group of people who like Irish Music, and play with them.