"Winning your home games is vital and that was an important win for us," he said.
"I thought we probably won the game because of our skills in the contact area.
"We bullied that area against a big pack and we looked to play rugby. Unfortunately we have to work on our platform to give us control in games.
"They came strong in the scrums but it didn't become such an issue. But we have got to deal with that and the boys are working hard in that area.
"We have come up against a very good side in Castres are they are not third place in the French league for nothing.
"They have a strong pack of forwards but we didn't go into our shell and kept playing. We knew that any turnovers or knock-ons - we wanted to play.
"I was delighted with a lot of good individual performances.
"I was delighted with all the World Cup players. I thought the two centres (Jonathan Davies and Scott Williams) worked particularly well together. They were pretty aggressive in the contact area.
"And everything has been said about George North - every time he gets the ball there is an air of excitement."
The Scarlets travel to Northampton Saints on Friday in Round 2.