Two of us are sharing an Apple ID. How do we convert to seperate ids?

1. You must choose one of you to get a new Apple ID.
2. Create the Apple ID as explained in the support document you posted from.
3. Sign out of the shared Apple ID on the devices of the person chosen to get the new Apple ID.
4. Sign in with the new Apple ID on said devices.

click here ➡️ Sign in with your Apple ID - Apple Support

Important notes:

1. All Purchases and subscriptions will remain tied to the old Apple ID, and the user with the new Apple ID will not be able to use them or access them unless Family Sharing is then turned on. click here ➡️ Set up Family Sharing - Apple Support
2. All Apps downloaded with the old Apple ID, will remain tied to that Apple ID, and will require it and its password to update. The user with the new Apple ID, can choose to delete the Apps and re-download them with their new Apple ID. For Purchased Apps, Family Sharing can be used to re-download them, and not have to pay for them again.
3. All iCloud files, Photos, content will remain on the old Apple ID. When changing Apple IDs, iCloud will ask if you wish to keep data on the devices being signed out of the old Apple ID. You may want to answer Yes, to keep the data so it can be synced up to the new iCloud account.