Read, read, read Ed Friedland's "Reggae Bass" book and find and listen to the songs of which he speaks. His book is an excellent and
comprehensive introduction to the role of the bass in not just reggae, but the whole history of contemporary Jamaican music, from mento ('50) to ska (early '60s), rocksteady (mid-'60s), reggae (late '60s to mid-'80s and beyond), and more modern styles like dancehall (all dates above are approximate, as styles overlap time periods). Contemporary Jamaican music only spans about 60 years, and the ska era to the present is only about 50 years, so there's not a lot of material with which to become familiar. And the same simple two-bar or four-bar bass line is used throughout the song, so there's only one or maybe two lines to learn per song. If you can play everything in this book, you pretty much know all there is to know to play reggae.
"Riddims," as Friedland explains, are the bass and drum parts--the backing tracks to certain songs. Often in reggae, the backing track of one song is used as the backing track of an entirely different song. Friedland explains this in more detail than I have room for here. The point is that, when you learn one song, you are learning two or three or more songs.
Hal Leonard has a "Bob Marley Bass Collection" book with bass lines from 19 Marley songs--I hope you know that you probably won't get through even one reggae set without playing a Marley tune, as Marley = reggae for most people. (I personally love rocksteady more than reggae, and a generous British cat, bassist Dave from Gravesend, has a wonderful collection under the name "oldwah" on youtube that is a great learning resource, and fun fun listening):
http://www.youtube.com/user/oldwah
Finally, become familiar with the concept of the "one-drop"--you play nothing on the first beat (the "one") of most measures. This is a simplified explanation, but this should become apparent to your ear from listening to even a few reggae tunes.
As another poster pointed out, the Studio One compilations from Heartbeat Records have many essential tunes. "The Best of Studio One" and "Full Up: More Hits from Studio One" fall into this category. "Downbeat the Ruler: Killer Instrumentals from Studio One" has backing tracks (the "riddums"), some of which you will recognize from the vocal songs on "Best" and "Full Up." And Trojan Records' 3-CD "Rocksteady" box set has a wealth of hits. "Best" and "Full Up" contain many of the songs that Friedland refers to. Add "Downbeat" and the rocksteady box and get "Legend" by Bob Marley, and you should be covered. Listen (don't just "hear"), allow hips and feet to get into the groove (reggae is definitely a "feel" music), and absorb.
Do get the reggae band's set list, because they may have more modern tunes that I haven't covered here. But the above should give you a solid foundation.
Hope that helps.