You and your buddy are probably in different kingdoms. Here's how you switch kingdoms so you can play with your buddy.
1. Go to the global map and in the top left is a button with a blue and red flag sitting on top of a map. Have your buddy do the same.
2. Decide whose moving. They need to know their kingdoms name and number which will be whichever kingdom should is in the middle of the kingdoms screen.
3. If you're moving to your friends kingdom, have him read you off the assigned number of his kingdom. You'll need to type it in to the search box at the top right.
4. Once the kingdoms loads, have your buddy go back to his city on the global map. Have him read you off his coordinates. The coords should read something like 100;X, 75Y. Type in these coords in the search box at the top right of the global map.
5. Once you do this, you should see your friends city on the map. Choose a spot next to him for protection.
Hope this helps!