updatedb is the command for updating the locate database. In reality, the locate database is usually the slocate database, and the updatedb command is often a symlink to slocate, using the -u flag or a similar option. Updatedb is usually run as a cron job.
While the updatedb should be sufficient for creating the initial database (the -u option is supposed to be default) it sometimes seems necessary to issue it explicitly.
The only other particularly useful option is -e directory where 'directory' is one or more directories to be excluded from the database. For example, to exlude the /mnt directory (which contains mount point directories for removable drives), you could modify the crontab entry like this: updatedb -e /mnt.
See its man page(s) for a complete list of options.