When ascending or descending stairs always use the handrail. To go up, start with your good leg and follow with the iWALK, going one step at a time. Then repeat until you get to the top. To go down stairs, the recommended way is to go down backward. Start with your iWALK leg, followed by your good leg and continue to descend one step at a time. An easy way to remember this is "Up with the good, down with the bad".
See below video for visualization: