I'm not a parent, but I don't envy you the task of keeping your daughter "safe" online. I know a guy whose job it once was to find porn and other offensive sites so he could add them to a company's "can't go there" lists for the firewall. It was a full time job, and in the end, could not be done by one person. Nowdays, you must automate the process. Even that is tough - notice that spammers, for example, have taken to intentionally misspelling stuff so it won't get filtered.
I do think it's great that you're thinking about this, though - too many parents don't. FWIW, my neighbors with kids follow the "public use" policy for family computers: Kids' computer use must take place where a responsible person can easily look and see what's happening.
I wish you all the best.
Science. If you don't understand it, don't talk to me about how it's going to end the world.