Each dataset hosted on Atlas has a page describing its contents and linking to related resources. Most datasets have a "downloader" map that allows you to browse the state and click a quad or image footprint to download files. Files can also be downloaded in bulk via FTP. For certain datasets, a web service is available so you can view the layer in an application without having to download all of the individual files.
The Louisiana Statewide Lidar Project provided high-resolution elevation data for the entire state—the first to do so with lidar. The dataset is available online through Atlas for public access. Extensive details of the project can be found in the publication, “The Louisiana Statewide Lidar Project“.