Rizford:
You should make sure that any of the Labels that come with ArchiCAD will do what you want. For example in the US version the Object Indicator_NCS Label will display the ID of an element.
The only way to create a custom Label is by writing GDL, which takes some time to learn. If you want to go that route, then I recommend starting with an ArchiCAD Label that is close to what you want so you don't have to script everything, but just modify parts of the scripts.
David