How to care for new born guppies?

just last sunday i went to the pet store and wanted baby guppies but the man said that if i got a male and a female then i could have my own for free... so he told me that there would be babies in 3 to 4 weeks.. well they were born yesterday so they came quite a bit early.. im feeding them crushed brine shrimp and there is about 12 babies what would you recomend feeding them? and how to care for them in the right way?