How to draw path line between two co-ordinates in Google Earth

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Google-Maps

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Google-Earth

Hi,

Currently i am working on Google Earth to plot some points, i have co-ordinates in excel file, i converted excel to .kml file and plot on Google earth. that's all fine till here.
Now i jump to my question:
Actually i draw all points but my requirement is to show transition(Lines) between to points eg.
There is some points A,B,C,D,E,F

A--> B--> C (A is connected to B and B is connected to C)
similarly
C-->E
A-->E
A-->F

so i have to show these transition in Google Earth by KML file which is generated from Excel file.
For reference and below are the transition points in which
4021--> 4023
4021-->3117
4021--> 4023
3117
Please suggest how to modify the excel file so that i can achieve this.