There are several ways of doing so:
The simplest one is to edit MyCharacter blueprint which you will find inside Game folder. Just go to Components section of Blueprint and change your skeletal mesh.
The Second way is to edit your C++ code:
It’s also simple but can be bit daunting if ypu never programmned in more general purpose language.
First find your GameInfo implementation file (cpp).
Here will be:
AYourGameInfoClass::AYourGameInfoClass(const class FPostConstructInitializeProperties& PCIP)
: Super(PCIP)
This is your constructor. Simply speaking without going much into detail class constructor is special method that have exactly the same name as class which it construct. Here you can initialize all your properties and do other things that must be done before class is used.
In any case you will find a line here:
static ConstructorHelpers::FObjectFinder PlayerPawnOb(TEXT("Blueprint'/Game/Cloth/Cloth_character.Cloth_character'"));
The part after the TEXT is path to your pawn blueprint. Can change it any other pawn blueprint you created (remember it should derive from Pawn Class or Character or anything that is in this hierarchy).
If I understrand it correctly ConstructorHelpers can be used to find any type of Object within unreal and then do something with it. (in this case we setup default Pawn Class in if clousure_.
Anyway I recomend reading some C++ books or tutorials. C++ is no that hard as it first appears