The tab in the online lesson is for the rhythm part, which is the only guitar part in the recording. It is an active rhythm, almost what you could call a "lead/rhythm" part, though the single note (lead) part is note very extensive. It's just 2 or 3 lead in notes before you play the chords.
The chords themselves are smaller shapes, or chord fragments. It's explained in the text, briefly. If you are having trouble following it, you can look at "Blues Rhythms You Can Use" and "More Blues You Can Use" (which is cited in the lesson text) for more thorough explanations. You will find a more extensive explanation of the theory in Blues You Can Use Guitar Chords.
My advice is to take the first two beats of the tune, with single notes and small chord fragments, and get that down. Look at the chord grid above it and notice which notes in the rhythm are derived from it and which are not. Then move on to the next small bit, beginning with the single-note triplet at the end of measure 1 and through the chord notes in the first 2 beats of measure 2.
Move to the next small segment. You'll see that it is identical to the opening bit you worked on, and the following piece is the same as the 2nd one in the tune. Play them and move on. Continue through the tune in small chunks like that.