What care must I take while washing the engine with water. I have never washed the engine

That would be a BIG mistake!! .. You should NEVER spray water on ANYTHING under the hood .. I don't care what anyone tells you, I've had to repair too many mistakes people make just like that! .. Plus washing the engine has absolutely no benefit at all, other than cosmetics!

You have already been given good advice! Your also talking about a hybrid vehicle.