The Portugal forward, who had set up Sergio Ramos to head the opener for his side in the 31st minute, helped turn the game back in his side's favour after Almeria had fought back to 2-2 in the second half.
In the 81st minute, he won a disputed penalty after he tumbled over Almeria goalkeeper Diego Alves in the area.
"I was angry with myself. I missed a penalty," he told reporters.
"I don't like to lose or to fail, I am a perfectionist. But I don't give up either and I was pleased for Karim's goal."
He picked up his second yellow in the last minute of the game after reacting to a provocation, kicking Almeria's Juanma Ortiz on the leg.
"It was an instinctive reaction, I know I made a mistake but I am human," he said. "These things happen in football but I have to learn from it.
"I have asked for forgiveness from my colleagues."
Real coach Manuel Pellegrini defended Ronaldo, saying: "His sending off his was perhaps fair by the letter of the law but he's the type of player who doesn't deserve to be sent off.
"He focuses on creativity and playing football, it's others who dish out the kicks. The red card was avoidable but it's a one-off and that's that."
