Please help me im looking for websites?

Question

place where you can enter dads name and find his kids

Answer 1

The closest thing you might be able to find is US Federal Census records - the most recent release is 1930.  I found it online at ancestry.com (you have to pay a fee) The census information is available for free if you physically go and search it.

You can find the census sites closest to you at http://www.cyndislist.com/

Answer 2

Normally, that type of information is confidential.. meaning, restricted, even off the internet, much less online.

It is far too easy to misuse such information for things like id theft or invasion of privacy.