I am trying to make a homebrew paladin subclass and I am trying to make this a Channel Divinity option for 3rd level....  but I am either missing something or not understanding how building the feat works.

What do I need to do to make this work?

• Sacred Weapon.

As an action, you can imbue one weapon that you are holding with positive energy, using your Channel Divinity. For 1 minute, you add your Charisma modifier to attack rolls made with that weapon (with a minimum bonus of +1). The weapon also emits bright light in a 20-foot radius and dim light 20 feet beyond that. If the weapon is not already magical, it becomes magical for the duration. You can end this effect on your turn as part of any other action. If you are no longer holding or carrying this weapon, or if you fall unconscious, this effect ends.

Just look at what Oath of Devotion does. It makes it as an action

Hey! Thank you!  

Could you tell me how you pulled that up?  Or did you create that as an example?

Sorry.  DnD Beyond noob here lol.  I appreciate the help!

Collections -> Create Subclass then select Paladin and Oath of Devotion as the base

Then Edit under Channel Divinity and again under Sacred Weapon

got it!  Thanks again!  You're awesome!