When we play clawhammer, we usually find occasion to add some rhythmic beats either between melody notes, or while melody notes are being sustained. In most music, the strongest beat of each measure is the first beat. In 4/4 time, the emphasis of notes usually follows the following, decreasing emphasis pattern: 1, 3, 2, 4. Therefore, the weakest beats in each measure are beats 2 and 4, so these beats are commonly played as a gently brushed chord. In our tablature, a chord is indicated by stacking the fret numbers vertically (the same thing is true for standard notation, where the notes appear stacked).
Your right hand will make the same motions to do the brush as it did when we played only single notes, but try to remember to do it gently, and just play 2-3 strings, rather than just the one:
(You can download this video file directly with this link: beginningbrush.wmv
You'll notice that we now assume you know that beat 1 is followed by beats 2, 3, and 4, so we're not going to show them any more. Similarly, brushes are implied by the stacked notes, so while they're shown in the first measure, we've dropped the brush symbol in the 2nd--same thing, though! Now let's combine single string melody notes with brushes--you should sorta hear Goodnight Ladies in here somewhere...:
(You can download this video file directly with this link: goodnight.wmv)