Found a puppy. What should I do?

I found this puppy wondering my neighborhood this morning. He the sweetest little thing. He has a color but no information. There was a family outside when I found him saying he has been wondering around the past few days. This family, was visiting from out of state and they are leaving to go back home today. I currently have him in my back yard. Can anyone help? I’m in round rock near I35 and McNeil. I’m open for suggestions. Please and thank you.