It sounds like you don't really know what to do so I highly suggest finding a friend who knows about this stuff if you can. But if you really can't find anyone that can help, I guess try reading the manuals.
I couldn't find any decent pictures of your device but usually in the back there are red and white connectors, each corresponding to left and right audio. You should connect the Wii's red and white connectors to those. Read the back of the labels so you know which inputs you are plugging them in to.