Sharing content with those not on your network
Sharing content with those not on your network is a bit more challenging. As you have learned, maps and layouts don't actually store the GIS data they reference. Instead, they point to the original data source. The data source can be a database stored within the project folder structure, or it might be located somewhere else entirely. It is even possible for a project, map, and layout to include multiple layers, all of which reference data in completely different sources.
This is why, it is difficult to share your work with those that are not able to connect to the same resources as you. You can't just send them a map or layer file because neither of those include the underlying data. You could possibly zip the project folders together into a single file, which you could e-mail or put on an FTP site for download. But that only works if you have all the data you used within a project that is stored in the project structure.
If only you...