It's basically HTML with attributes. In his example "<tr bgcolor="{IncidentColour}"><td>Description</td></tr>" the attribute {IncidentColour} is used to set the fore color of text. Most often though people use pictures like blocks, circles, and arrows to start the row. You would create a picture, say a yellow square, a greed square, a red square and then name them the same as the values in {IncidentColour}.. Then when you use the following code "<tr><td>images/{IncidentColour}.jpg</td><td>Description</td></tr>" you get a colored square followed by the word description. The <td> and <tr> are for tables so things evenly space out. There are a bunch of example somewhere of what others have done.
You may end up doing many of these so it might be worth the time to work through it and get exactly what you want the way you want it. The samples given here are just a start, there is so much that can be done.