Before you ever get to turn, you need to move on flat ground. To the lift, off the lift, around the base area. On a snowboard that means skating: front foot strapped in, back foot free, pushing yourself forward like a skateboarder. It feels dumb and clumsy the first ten times. Everybody looks silly here.
Strap your front foot in and leave the back foot out. Put the back foot on the snow next to the front binding and push gently. Let the board glide, then push again. Keep most of your weight on the strapped-in front foot. For short glides, rest the back foot on the stomp pad between your bindings. That's also how you ride off the chairlift.
Here is a quick tutorial that covers skating and one-footing:
Source: Ed Shreds · How To Push (Ride With One Foot) On A Snowboard
Key tips
- Push with your back foot behind the board, not in front of it
- Keep weight centered over the front binding. Leaning back makes the nose wander
- Rest the back foot on the stomp pad for glides longer than a few meters
- Practice small pushes on flat ground before trying a gentle slope
- Watch for other people. You can't stop quickly with one foot out