If the TimeLiner window is not already open, click Home tab Tools panel TimeLiner.
Click the Configure tab, and click Appearance Definitions.
Click Add.
A new appearance definition is added to the bottom of the list; it will be highlighted, enabling you to enter a new name for it.
In the Transparency field, use the slider to set the transparency level, between 0 and 100 (where 0 is opaque and 100 is fully transparent).
In the Color field, double-click the color to open the color selector. From here, either select one of the basic colors available, or click Define Custom Colors to define your own color choice.