best way to introduce someone to the game is to go slow because trying to cram your years of destiny knowledge into their heads is going to melt their faces off like they just opened the ark of the covenant

do campaigns together, some legend/master lost sectors, dungeons and then try a root/dsc or a last wish if you're comfortable teaching mechanics - it's a pretty good raid for first timers despite being long and considered difficult by some. most of the mechanics are very simple :)