Once upon a time, you could only put one table in a given FileMaker file. To set up relationships, you had to link the files in relationships and current FileMaker systems have maintained that capability as it is often necessary or at least advantageous to use more than one file in a database system.
Open Manage | Database | Relationships in File 1.
Click the icon at far bottom left (Tool tip in FileMaker 13 reads "add a table"--not technically correct) to add a new Tutorial: What are Table Occurrences?.
In the dialog that pops up, select "Add FileMaker Data Source" from the Data Source Drop down.
Use the dialog boxes that open to find and select first File 2 and then the table defined in File 2 to which you want to connect.
Now that you have an occurrence of this table from File 2 in File 1, you can define a relationship to it or base a layout on it just like you would any table defined directly in File 1.
Thus, you can set up a list or table view layout with this new occurrence selected in "Show Records From" to list all records from that table. Or you can set up a relationship to it and then use a portal to the new table occurrence on a layout based on table occurrence that you linked to it. And an X operator instead of = can produce a portal that lists all records in the portal.
You can also create value lists that list data from a field or pair of fields in this table.
Wow. Thank you very much! I am just really starting to use FileMaker to help run my business and your prompt reply is very much appreciated.