I have a wolf fang pendant but how do I use it and where. I know it’s used with management cards..

Once you are appointed with a presidential title and are in charge of a national building, you can view the building and click the blank card tiles at the top. This will open up another screen to which you can now use these items to purchase a maximum of 2 cards per day (the other 2 comes from the red cards you have personally unlocked yourself). The fifth card doesn't appear to be in use at this time.