I currently have several databases (SOQs, Vendor Firms, TC References, & Projects).
I would guess that you have multiple tables in a single file. A database can be a single file with a single table, a single file with many tables, many files with one table each or many files with many tables each....
To get help with your portals, you'll need to describe what you did when you tried to set them up. What relationship did you define? On a layout based on what table did you add the portal? Did you specify a filter expression for that portal? What data do you have in the match fields you specified in the relationship? Do they really match values?