You play on Facebook:
If your friend already plays the game, they will appear in our friendlist in the game automatically.
If your friend doesn't play the game yet, you can send them an invitation to the game. Open the game Inbox and Gifts and click the button Invite Friends.
You play on our web site solitairesocial.com:
You need to know your friend's ID to add them to your friendlist. Ask them to copy and share it with you.
Then you will need to open the friends tab and choose the Add friends tab. Paste the ID, find your friend and add them.
You can also add random people to your friend list there.