Categories and sub categories help please

I am new to WordPress and after running our site for a while, I have found that I set it up incorrectly. I need to make categories and sub categories an example is I wish to have a category one time entry, another daily, another instant win, then sub categories of the type of sweepstakes ie cars, homes etc.

Currently I started page as all different categories without a parent then sub.

Can anyone advise me on a plugin that will allow me to do this after already having so many posts …I know it’s closing the door after the horse is out but I’m hoping to get lucky.

Any help will be appreciated.

https://win-it-world.com/