One of the main navigational aids is to apply a structure file to the data file, which provides one or more layouts in which to present each record in a much more user friendly way; see Creating Structure Files and Layouts for more information.
Structure files can be specified when a data file is opened, or you can load and unload structure files to a data file that is already open.
There are also navigational arrows (or you can use the cursor keys) to move from one record to the next. You can also jump directly to a record by entering the record number in the Record Number box.
For larger data files, an easier solution is to use a filter. The filter allows you to use multiple criteria in order to filter the records that are displayed, either by only including matching records, or by omitting the matching records from view. After the filter has been applied, you can switch between the entire file and the filtered results.