With Social Hub we have two options to add friends
Retrieve the invite link from Soda app and share it our contacts. We can also copy and paste it everywhere we want to share it. In this forum we have this discussion were we share (paste) our invite link so other users can click on it and add us
send invites to players we meet in Soda events (Soda Team, 4 in a row, weekly contest, Kimmy's Candy Hunt, Shipmates, Soda Cup etc). Simply click on their avatar pictures and select "add friend". more infos here