Add the person to your buddy list. Then go to your buddy list and next to their name click buddy credit.

You need to first add the person to your buddy list - you do this by going to their profile and then clicking on the  "+ Buddy" button that appears up by their name.  Once you do this you can then go to your buddy list (under My Account, My Lists) and then there will be a button you can click to send credits.

Hope that helps.  :)