Really a rookie. Inside city screen, hover over the city banner where the name is, if using EUI, or hover over the happiness icon if using vanilla UI. You might see the unhappiness of this city.
If you are using events, I can't help. I dislike them, so I I uncheck it when setting up. Pillaged farms and mines are the worst.
For gold you have three paths. Merchants, befriending CS, trade routes (good with tradition), city connection/lighthouses/monopolies (good for progress) and tribute, pillaging, policies (good for authority).
If you have too many units, gift some to CS. If you are too short on gold, consider selling your last luxury copy, or strategic resources you don't use. As a last resort, sell a building.
EDIT. Hey, hope
this helps.