If your team member sends you a Bubbles IQ challenge, you should be able to see it on the right column of the Facebook's home page, where you normally see all the Facebook game requests.

Clicking the Challenge-notification will take you straight to the game.

You can challenge your team members who haven't played the game yet this week; click the "Challenge" buttons on the left side of the game after the "Friends" -score list. If you click the "Challenge team" button, notifications will be sent to all of your Bubbles IQ team members.