Need help assigning tiles

Can someone please tell me how to take a tile away from one settlement and give it to another? I know how to do it in BtS, but this is the first version of Colonization I've played where it was even possible, and all my buttonsmashing attempts have failed.

If I understand your question correctly, you would just have to put a worker in city A on the tile currently occupied by a worker in city B. This is done from within the city screen in the little window in the upper right corner.
Then of course you should check what the worker in city B is doing now.

Hm, could you please describe a little bit better what you are trying to do?

Is my understanding correct that you try to grab a sector/territory from a foreign colony nearby? If yes, you need to expand your "culture". Some of the buildings grant culture (typified by a crown - please have a look into the colopedia) and enable you to expand your colony.

The difference between Civilization and Colonization is that in Colonization, you need to assign a large diversity of jobs to every single worker in your colony. Some workers are specialists and perform better their task (like expert tobacco planters produce more tobacco than any other worker who would be assigned to tobacco planting).

• If the two cities which share tiles in their radius belongs to you, then you can "push" a worker out of a colony "A" in assigning a worker from the other colony "B" to the same tile. But then the AI will automatically assign a new job to the worker in colony "A" who's been pushed away so I would advise you to check what happened there. That's Commander Bello's answer.
  
• If the cities in which you want to grab the land belongs to a foreign power, then you need first to bring that land within your territory as only tiles which are within your borders can be worked on. That's Schmiddie's answer.
  
• Finally, the tile can also belong to a native nearby village. In which case you can either buy the land or steal it, which would make the natives angry and prone to raid on your colony later. The natives don't have official borders, but they still consider the surrounding territories around the village to belong to them. So be careful with this.

Thanks for the answers everybody. Yes they were both my colonies, and I coulda swore I tried the "move the citizen to the tile in question" before I asked.

Anyway, I got them all where I want them now. Unrelated follow-up question: Very early in this game I saw a wolf wandering around the edge of Russian territory- with a Russian banner instead of barbarian. Can wild animals be captured?

Great that the issue has been solved.

No, animals cannot be captured but if I remember correctly there is an event which grants you a wolf. But I assumed that this should not happen for the AI.