I cant believe they sold you that many fish at once
I hope your succesful with them, expect a few loses - its normal when your doing a fish cycle, usually the amonia rockets up, and some of the more delicate fish cant cope with it. I do recommend you get yourself a API master test kit - as the dip stick/paperones are rubbish and not at all accurate.
It dosen't sound like that is a very good shop. You should leve the tank for at least a week, i left mine for three. Also you shouldnt get nearly so many fish at once. It soulds like that shop just want to make quick sales, if i were you i'd find somehwere else in the future.