Attach Sprite to Actor/Character

I have a sprite which I want to attach to my character. Sooo… how do I do that?

Add a sprite component to your character.

I know but how do I do that in code?

In your character class header, you have to create a variable of a type UPaperSpriteComponent* as shown below:

UCLASS()
class MYPROJECT_API AMyCharacter : public ACharacter
{
  GENERATED_BODY()
  
  ...

  private:
  UPROPERTY(EditAnywhere)
  UPaperSpriteComponent* CharacterSprite;
}

Then, in your constructor, you have to construct the component and attach it to your RootComponent.

AMyCharacter::AMyCharacter()
{
    // Set this pawn to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    PrimaryActorTick.bCanEverTick = true;

    CharacterSprite = CreateDefaultSubObject<UPaperSpriteComponent>(TEXT("CharacterSprite"));
    CharacterSprite->SetupAttachment(RootComponent);
}

Now you should be able to spawn your character in editor and set the source sprite for it. Good luck!