To add friends in the Stryk app you can:

1. Tap on any profile of a trader that you find in the channel or in trending (home screen). Once it takes you to their profile you can tap on +Friend (in the top right corner) and send them an invite with a short message. If the user accepts the invitation, you will get notified and you will see your new friend on your friend list.  

2. You can go to your profile by tapping on the head icon (in the bottom right corner), then click on FRIENDS > Find friends and search for users with their usernames.