Can someone plz tell me how to set up a trade shop.... and does someone know wuts the price of a doppler card +\-

you have to be a merchant to set up a shop, follow the skill tree
http://iro.ragnarokonline.com/game/jobmerskilltree.asp

oh k thnx, and do u know were to get a dopler card or how much it costs?

doppleganger.
cost depends on how much are going around town.

then wut do i need to kill and where to get it? ( il probably wont be able to kill it cause im still lvl 89 :P)

you kill doppelganger to get the card, you can get it in geffen dungeon