sabith pocker
You have to export users as CSV, then import them to Okta. Users will have to sign up in Okta and set Okta password which they can use going forward. New users will have to be added in Wordpress and Okta as far as i know or do some setup to hook into wordpress create user and link the same to okta API as well.
CSV template can be obtained from Okta CSV import popup, it has a link to download CSV template. For my case I wrote a Wordpress plugin for the same.