The starter solutions are not designed to share data with each other. You would need to make pretty significant design changes to accomplish that with the starter solutions. You may actually find it easier, if you are new to FileMaker database design, to design your own solution from scratch. I think there's also a solution available that has already set this up, you might web search for "starting point FileMaker" and see what is currently available.
In order to do what you want with a pair of starter solutions, you'd need to do one of two things:
1) Merge the two files by moving the tables, layouts, scripts from one file into the other and redesigning the relationships in Manage | Database | Relations to incorporate the new tables. You'd likely find one or more pairs of similar tables--one from each starter solution, where you'd eliminate one table and use just one of the two in all parts of the file. (You might have two contacts tables, for example). Redesigning layouts and scripts to refer to different tables are not quick, simple tasks. In fact, by the time a developer acquires the skills to do this, they usually are no longer interested in combining starter solutions as they now have their own ideas on how to design such a database anyway.
2) Add external data source references that refer to tables in the other file. This is much simpler than 1) but still requires extensive reworking of the file's design to incorporate that new external data source based table occurrence into the structure and function of your database. You're still looking at extensive redesigns of layouts and scripts to refer to a common table of data.
This is a pretty complete article about the steps in merging databases.
It assumes you have Filemaker Advanced. And it is about FMP v11. But it illustrates the complexity.