When the blue dot moves on the red line, What is the demonstrating?

in the spreadsheet, click on a cell, then type the numbers or text you want and press enter or tab. to write data to a new line within a cell, press alt + enter. to enter the same data in several cells at the same time you must select the cells in which you want to enter the same data, in the active cell write the data and press ctrl + enter.

you need need more details so we can understand what your asking us.