"The first two goals were down to bad defending and you get taught harsh lessons in the Premiership if you make mistakes and don't take your chances," he said after the game at The Valley.
"Obviously we had to chase the game and that left us exposed but we have got to keep believing in ourselves and I felt some of the players were beginning to doubt.
"Last season we only lost five matches but there is a huge gap between the Football League and the Premiership.
"We haven't got the resources to sign a lot of top players but the ones we have got are very honest. We've obviously got to do a lot better than we did today and especially in taking our chances.
"Everybody has got to stand up because nobody will give you any sympathy, we must stick together and once we get that first win under our belt, I am confident we can push up to the league.
"We always knew it would not be easy and so it has proved."