This link should automatically open the Social Steps app on your phone if it is installed. However, if you still endup here try clicking this link here to open your friend's page:LINK TO THE APP
The link opens your friend's Social Steps profile. From there you'll find a "send friend request" button. Tap that button and wait for your friends to accept the request.
Wait for your friend to accept your request. You can then see each other's steps and start your friendly competition!