Select text object from above toolbar and point out the location where you want to add message on your label. Double click on text object to add or modify text from text properties. Text properties includes following tabs:
General : Select data source either Manual or Data Set (Data Set Series feature allows to generate the multiple copies of labels with text and barcode value).
Color Effects : You can adjust fore color and back color with Solid color, Gradient, set transparent etc.
Others : You can set text angle, border etc. as per need.