hehe,
the easiest way to put your SG on a post situation is to put him on the PF or C position.
another way is to have a look in your playbook.
the easiest way on a 2-1 fastbreak is it fill your lanes. Spread the distance between you and your teammate and the CPU will run to you. your teammate will automatically cuts to the basket, if you pass to him.
if you let your SG or SF brings the ball in fastbreak, your PG usually stops at the 3 Ptline. So dish the ball with an outlet after a rebound to your pg and run your fastbreak. 8)