Within Configuration Manager 2007, once a package and its associated programs have been created and distributed to its various distribution point, you need to get it to the clients. Advertisements do this in two ways: not only do they alert clients that the specific package is available for them to download and install, but it provides them with a path to doing so. Additionally, advertisements provide you as an administrator, with a means to push a mandatory (assigned) program to clients.
The following flowchart provides a high level visual workflow for creating and modifying advertisements for software distribution in Configuration Manager, and the links at the end of this document provide detailed information about the process.
Creating and Modifying Advertisements: End-to-End Workflow