OK I got it to work now, it was really confusing reading thru different methods from different ppl while searching around. It actually is much simple than people tell you. Just in case someone like me who have no idea how mods work with Sims 3, here what I did that works well for me.
Install sims 3 and the expansions and/or stuff packs.
Patch up to latest.
Download Monkey Bars, and use it to install framework.
Put all the mods into mods folder in the core Sims 3 mods folder.
Copy d3dx9_31.dll from Sims 3/game/bin, and paste it into each Expansion and Stuff pack game/bin folder just to be sure.
It should work.