riz u play both strings together,
and is the tab u posted of a diffrent tuning??
i think it shud be b instead of d, or u missed out a string in between.
well pull off means, simply u play a note and lift ur finger off the board, so that the string continues to vibtare,
and hammer means u play any note and then hammer ur finger on to another fret,
and there r plenty of lessons on igt,
and u can also try these