bringing a little bit of dirt and grass from outside is a good idea. (when you get to that point)
basically, you are trying to get your baby to understand what you want him to do, so however you can communicate clearly with him will help him understand what you want him to do and make it less frustrating for you and him.
let us know if you need more help, i tried everything when i trained milu, i didn't know what i was doing(she is my first dog) some things worked and others didn't. i can share more with you if you need more help.
good luck!