Click on the Line Plot icon on the main toolbar. Select the Hole_ID column in your data-set as the grouping column and a depth or Z coordinate column as the continuous variable. Leave the variable format as numeric.

In the next dialog select the drillholes you would like to display and how you would like to display them, eg. stacked on top of each other, tiled, etc.

For more information on how to use the Line Plot tool and a list of the various Line Plot options, see:
Line Plots 5.2.pdf

Alternatively, in ioGAS version 6.0 and later, you can utilise the new Downhole Plot tool – which displays each of your drillholes in a continuous vertical line plot which allows for easy comparison between holes.