Search your friend's name, and click next to the profile picture of your friend.
The other member can then either confirm or deny your friendship request.
When someone has sent you a friendship request, this notification will appear at the top of the NeuroNation green side bar.
Click on the request, and confirm it by pressing the green tick beside your friend's profile picture.
If you like to not accept a friendship request, you can do this by choosing the red cross instead.
An alternative way is to go to your profile and click 'Invite Friends'.
You can either find friends knowing the personal email address which they signed up with, or by using their NeuroNation username. Just enter either your friends email or NeuroNation username in the friend request form, and submit the request.