There or It ?
We often use there when we mention something for the first time, like the picture in this example.
There was a picture on the wall. It was an abstract painting.
We use it when we talk about the details. It means the picture.
Here are some more examples.
There's a woman at the door. ~ Oh, it's Aunt Joan.
There was a dog in the field. It was a big black one.
There's a new one-way traffic system in the town centre. It's very confusing.