'Trilling' is a fast form of 'Hammer-On's' and 'Pull-Off's'. It is done by repeatedly hammering on and pulling off. To peform a trill fret the 5th fret, G-String with your first finger. Pick that note, then hammer-on the 7th fret with your third finger, then pull-off, then hammer-on then pull-off repeatedly, at a very fast pace. e|------------------------------| B|------------------------------| G|----5h7p5h7p5h7p5h7p5h7p5h7---| D|------------------------------| A|------------------------------| E|------------------------------|