This is one of the toughest config to do, more i read about it more i get confused.

What i want to do is simple but don't know where to start.
I operate national only, no international shipping. I just want to add 2 shipping method for customer to choose during checkout. One is standard shipping, the other one is express shipping. Also shipping rate apply for up to 5 items.

For instant
standard shipping rate is $10 for 5 items
if there's 7 items it will be $20

Thanks