When you first register for Klout there is an opportunity to add other networks to your Klout account. If you decide to skip that stage, you can always add networks later.
In order to add networks to your Klout profile, please go to top right hand corner of your profile, hover over your name, and a drop down menu will appear. Click on "Settings."
Then click on "Connected Networks."
Click on "Connect Now" next to any network you would like to link to your Klout account.
Click on the "Unlink" next to any network you want to remove from Klout.