On the Access rights tab, which is present when you have selected a new or existing method in a data source in an application in the Application browser, you can restrict access to this method, dependent on the user (login name in Windows) and its assigned role.
Click here for information on how to edit properties in general. On the current tab you'll find the following settings:

Access

Here you may define which Roles have which Access rights to this method. You can indicate for each role whether no access (None), Read access, Write access or Full access must apply. Access rights for a role associated with a method can never supersede access rights for the same role associated with a dataset or database. If a role is not linked to this method, then each user linked to that role has full access by default. If no role is linked to the method, every user linked to a role has full access. A user without a role always has full access. Users are assigned to roles in the application setup.

Some access rights make nonsensical combinations with certain methods, like a Create new records method with read-access. But it shouldn't cause errors. The result is usually that different access rights have the same effect. For Term search and Free text search methods for instance, there are basically just two choices: you want to allow searching on this access point, in which case Read, Write and Full are equally applicable and have the same effect, or you don't want to allow searching. in which case you choose the access rights None and the method won't even appear in the access points list. And for the Create new records method the access rights None and Read have the effect that the user is not allowed to create new records (the icon for it won't be present), while Write and Full do allow creating records. An overview of all combinations can be found here. In general, you'll be able to use common sense to figure out what effect certain access rights will have on a method.
Do note that applying limiting access rights on method level may not be as save as applying them on database level. For instance, excluding users from being able to create new records in a data source, still allows them to create new linked records in it from another data source to which they do have write access! If you want to make it impossible for certain users to create records, you are better off setting these access rights in the database setup.

See also

Security in Collections