pull the carb, then the 4 bolts that hold the intake to the jug, the reeds are the "valves" of a 2 stroke, they open and close to allow fuel/air into it, and commonly break a "petal"
you should use new gaskets, and do a leakdown test after any intake work, it's a common area for airleaks, which will seize your motor if it sucks air and runs lean
and dont over tighten those 4 bolts when re-installing, they strip easily
and from your question about "what are reeds" i'd say you needa look up "rocky mountain atv" on youtube, they've got some great "how to" vids on stuff as simple as changing reeds, oil, clutches cleaning carbs, jetting ect, ect.