The modification adds missions involving Franklin and Lamar. You need to get to Franklin's first residence, indicated by the green letter "F" on the map, and, approaching the sign behind the house, press the key combination F3 + X. Select a mission from the menu that opens.
Controls: - keyboard shortcut F3 + X: open/close menu - Numpad 2 and Numpad 8 keys: menu navigation - Numpad 5 Key: Select