I'm looking for a free SQL DB Template for a Social Network?

Without knowing what information you want to store regarding the social network or how you want to use it, any 'generic' schema is unlikely to be very useful. It's like saying "Get me a car" without giving any details such as how many passengers it should hold, whether it's for local/long distance/off road driving, whether cargo capacity is an issue, whether fuel efficiency or raw power is more important, etc.