How can I do to appear one line after the other?

If you add an entrance animation to a text box with bullets (or just multiple paragraphs), you can set the animation "By paragraph":

With that setting, the bullet points will appear one after the other. The attached file has an example of this.

By default, a bullet point will appear immediately after the previous one. However, if you expand the animation on the Timeline, you can adjust the starting time of each bullet point: