Celtic music consists of many types of tunes traditionally played for dancing, but this infectious, toe tapping music is mostly enjoyed by the people who play it.
Reels, Jigs, Polkas, Slip Jigs, Hornpipes, Waltzes, Barn Dances…. Tunes are generally played together in sets of 3 or more different melodies.
There are many accomplished players who don’t read music, they learn by ear or directly from other players. This ‘oral’ tradition of learning music is how tune learning workshops generally tend to operate. Having something to record audio on (like a phone) is always useful but a lot of people rely heavily on musical notation. Click this link for more advice on learning by ear
Try and develop as many different tune learning methods as you can.