yeah there are some tabs/music sheets that show when to perform up strokes and down strokes but most of the tabs on the net take the notes and chords as more of a priority as the rhythm is something that is more natural just like when you tap you're feet and hands to a beat of a song.
you dont know the exact drum pattern yet you're able to unconsciously tap you're foot when its the bass pedal or tap the desk when its the snare, and thats basically the same with the guitar because in most songs it will start with a down stroke and followed by an upstroke and will continue in that pattern with the chords only changing
so basically strum you're guitar like you would tap youre feet, do it to the beat
rhythm isnt really something that can be taught you either have it or dont.
thats not to say lessons dont help but generally you either have or you dont, much the same as when people say there tone death, lessons will help but it wont coem naturally.
hope iit helps a bit, basically dont think to much about what youre right hand is doing concentrate on the chords and what youre doing with the left hand and hopefully the right hand will coem naturally
