Does anyone know a good way to go about taking a program made in PowerBuilder 6 and converting it to PowerBuilder 10.5?
Run the Migration assistant in 10.5 and see what it thinks of your code. Main thing to look out for going from 6 to 10.x is the switch to Unicode. Migration will handle most of it, but if you're calling external functions you'll have to tweak them. I think the Migration Assistant flags them.
Migration's been covered here a couple times. See How to upgrade PowerBuilder code? and Migrating from Powerbuilder 6.5 to 10.5 .