Look up this section in Filemaker help to get you started on the basics: "Editing record access privileges". There's a section in that help article titled: "Entering a formula for limiting access on a record-by-record basis" you'll want to pay close attention to.
If you read all that and still have questions, feel free to post back here with them.
I'll check it out.
Tagging on as I am looking to do the same. I followed Phil's recommendation and now my user only sees the records I want them to (for the most part) but the other records are still there all the fields just show 'no access' Is there a way to hide those all together?
An over simplified breakdown of my setups is...
3 tables: Customers; contracts; support tickets
the relationshps are: Preferences::portfolio--Customers::Portfolio; Customers::Portfolio--Contracts::Portfolio and Contracts::contract--Support Tickets::contract
I created a preference page where the user can enter the Portfolio they manage. By doing so it allows them to see their support tickets. The two problems are that they can also see other records as 'no access' and if a contract is not assigned to a portfolio they can see that contract as well. I only want them to be able to see the support tickets that are tied to contracts in their portfolio. My guess is I need to write a better formula for the privilage set. Currently for viewing records it is just Preferences::Portfolio = Customers::kp_ID_Portfolio
Any help is appreciated.