You should see a file called MainScene.h and another file called MainScene.m. Open the header file (which has the .h extension).

In the header file, add a few lines of code between the @interface line and the @end line. The header should look like this:

@interface MainScene : CCNode
{
  CGSize winSize;
}
+(CCScene*)scene;
@end

Then, in the main file (which has the .m extension), some lines of code should be added between the @implementation and @end lines. It should look as follows:

#import "MainScene.h"

@implementation MainScene

+(CCScene *)scene
{
  return [[self alloc] init];
}

-(id)init
{
  if ((self=[super init]))
  {
...