Well done for asking for advice early on 
A few quick points:
Never put Heroes of the same colour next to each other in defence.
And kashhrek heals either side of him, so he’s not good on the wing.
Level up kashhrek before skittlskull.
With what you have at the moment, I’d go left to right
Skittlskull - Boldtusk - kashhrek - bane - Balthazar
Find a good teaching alliance if you don’t have one already 
Have a look here for loads more help:
And…minor point… could you spell check your title? That’s just a personal favour, thanks