Yep, Flooz is an online currency that you can spend at a select list of stores (most are cruddy, overly expensive stores, except for TowerRecords.com and BarnesandNoble.com). You need to create an account at Flooz.com in order to have it/collect it/earn it/spend it.
If you're talking about the American Greetings Flooz offer, AG sends you a personalized link to collect your Flooz - when you follow the link to collect it, you'll be prompted to either log into an existing account or create a new one.
For the most part, Flooz sucks. There are a few good stores that accept it, you usually can't use coupon codes with it and they're constantly adding and dropping stores. And Flooz customer service stinks, so if you have a problem using it, you're mostly out of luck.