The cloudiness is caused by bacteria in the water.
When you put fish into a new tank, the water gets contaminated by ammonium that the fish secrete (ie fish poo). The ammonium is converted by bacteria into nitrites, which are then converted by another type of bacteria in nitrates (which are far less dangerous to the fish). The bacteria help create a better environment for the fish, but it takes time for them to get established, and there may be a few days where the bacterial growth makes the water look cloudy.
A week doesn't seem like too much time to me, but it depends on the size of the tank, how many fish you have in it (and how big they are), what type of filters you have in the tank and other factors.
From my experience with fish, it is a good idea to find a local expert who cna help you. Look for pet stores that sells fish, and go in to a couple. Find someone who seems to know what he is talking about (not just someone who is interested in selling you stuff). Don't be shy to ask other people who are there buying fish, most people will be more than happy to give you some advice.