The best way to find your connection to any ancestor is to research and build from the bottom up. I see that you have added your parents and carried one line back a couple of generations. So you already know how to research, add and connect profiles.
Continue on the way you have started. As you add more ancestors you may run in to a profile already on WikiTree. When you connect that one to your known ancestors you gain all the ancestors from that profile. In that way, which is pretty simple, you may find the link you need to John Smart.
Have fun researching and adding names and come back here (G2G) whenever you have more questions.