The lead guitar in this song just plays simple little fills. This is quite typical in Reggae, where going off on epic solos to a barrage of exploding fireworks in shiny codpieces is generally not the done thing.
Instead the lead guitar plays little lead fills that complement the overall groove. Although this is relatively easy guitar work, you still need to be tight with the timing, and it's not as slow as you might expect from a chilled reggae song. The slides in particular are quite fast.
Practice the fills on your own at first, and when you feel you have them down, loop the ActionTab and play along. Getting into the rhythm of the song will help you develop your sense of timing. If you aren't used to reggae beats this will be hard at first. Just keep at it, and you'll get it.
Main Fill - This is very short and consists of 2 main parts. First is the slide up / down, and hold the notes at fret 7. Then secondly, play this little lick. Repeat.
The Outro Fill is exactly the same, except the little lick is palm muted. This fill is repeated until the end of the song.
Middle Fill - This is also short and simple. It is played around the middle of the song.
We used a clean electric guitar (i.e. no distortion) with light reverb but quite a lot of delay. This gives a nice sound, particularly for this little palm muted lick during the outro fill. You don't need these effects, but they can help you get a good sound.