how to make required plane text fields or required firsrtName and lastName fields in users profile? I want to during the registration and profile changes were required. Maybe there is any plugin for this?
For custom fields that you add to users under settings>users>fields, you can control whether the field is required by clicking on the small gear icon and selecting make required. With built-in fields such as firstName and lastName, make required cannot be controlled. Within the CP, at least, you would need to look for a plug-in solution.
On the front-end, I would suggest a writting javascript solution that simply validates that the fields are not empty before submitting the form (or before enabling the submit button). Have a look at jquery's .on('click') or .on('change') functionality for more info.
