"We are looking for a supermarket."
Translation:Wir suchen einen Supermarkt.
That's not grammatically correct: aussehen is a "separated verb" (trennbares Verb) and when it's conjugated, the prefix goes at the end of the sentence (or of the clause in case of complex sentence).
Therefore to be grammatically correct, it should be "Wir sehen für einen Supermarkt aus".
Furthermore, "aussehen" doesn't go with für, and it doesn't mean "look for". It means "look like" or "seem" and used to describe the appearance.
E.g. Du siehst jung aus. You look young.
Es sieht aus, dass du müde bist. It looks like you're tired.