Time Sequence diagram and new thinking

I 've been learning UML for a long time, but I 've been stuck in books. He is not actually used in the project. So there is really little practical experience ..
I have been reading Enterprise Java with UML for a while. It should be said that this book is a very good book, and the only difference is that his example is really very failed. Maybe I have read this question several times to understand his example. After carefully reading this book several times, I have a rough outline of the software development process. Especially, the role of UML in software development has become more profound.
Each use case in the book corresponds to an activity diagram with a sequence diagram. The timing diagram will be updated constantly based on the project design progress. After reading it, I thought I had understood it... Later, when looking at the design pattern, we will see a pattern sequence diagram. Each object will have a new process when calling other objects .. So at this time, my thinking is going to be blurred .. Why is there no new process in the sequence diagram in Enterprise Java with UML? Isn't it a new process in the sequence diagram? With this thinking, I Google a lot of time sequence diagram materials. But still cannot give me the answer ..
The pause here makes me feel overwhelmed. For the time sequence chart data that comes out of Google on dozens of pages on the Internet, it is a method that Datong Xiaoyi uses to describe the time sequence chart. So I kept asking myself. Why do I want to display the new process in the time sequence diagram? Because it is not new, how can there be instance objects? How can I call methods of objects without objects ..
I accidentally clicked it again later.ArticleAn example of an analysis system design. The time sequence diagram above is displayed. Suddenly enlightened. In the past, I was still confused. Look at his design sequence diagram, just shows the call Relationship Between Simple objects .. Why. Because it is only in the conceptual design phase. Why do we need to consider the instantiation of a class in the conceptual design stage. In the past, the overall situation of a system analysis was not well adjusted. With a detailed design perspective, how can you find new in the conceptual design sequence diagram. The sequence diagram in the design pattern is actually in the detailed design stage. Of course, a class instance will be considered...
In the past, I still could not really understand the three design views that matrin master mentioned: Concept view, specification view, and implementation view.