Trying to create a new subclass, but I have no idea how to do the options so that one can choose the element. Help!

Show me what you got now and I'll try to help you with what you got as a base

• This homebrew Subclass does not have the necessary class features with the correct required levels.

"My lineage was bourn out of the Planes of Fire. That flame courses through my veins and not even death will quench it."

-Valath, Fire Sorceress

Sorcerous Origin

Sorcerer Origin

Beginning at 1st level, you are deeply link to one of the elemental planes. This link is your sorcerer origin. When you choose one of these, spells that does that type of damage, you will add your Charisma modifier to. Also, you can use a sorcery point to change elemental damage of a spell that is not of your origin to that of your origin.

Elemental Origins

Choose one of the following elemental types:

That is it.

Quote from RunnamucMessin >>

This Subclass cannot be shared with the community for the following reasons:

• This homebrew Subclass does not have the necessary class features with the correct required levels.

Remember, private homebrew is automatically shared with other users in your campaigns and does not need to be shared with the community for players to access.

 

Base Class:Sorcerer

"My lineage was bourn out of the Planes of Fire. That flame courses through my veins and not even death will quench it."

-Valath, Fire Sorceress

 

Sorcerous Origin

Sorcerer Origin

Beginning at 1st level, you are deeply link to one of the elemental planes. This link is your sorcerer origin. When you choose one of these, spells that does that type of damage, you will add your Charisma modifier to. Also, you can use a sorcery point to change elemental damage of a spell that is not of your origin to that of your origin.

Elemental Origins

 

Choose one of the following elemental types:

 

 

 

That is it.

 I don't really know maybe make a bunch of different modifiers and classify then as options for custom lineages so that people can choose from them and just trust they'll only choose one and tell them to and then the rest is just adding the charisma modifier

For instructions on how to properly set up Options, please see the Homebrew Subclasses & Species FAQ #1: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq). Sorry, I would have responded sooner but I didn’t realize from the title of the thread that you needed help.

Quote from RunnamucMessin >>

This Subclass cannot be shared with the community for the following reasons:

• This homebrew Subclass does not have the necessary class features with the correct required levels.

Remember, private homebrew is automatically shared with other users in your campaigns and does not need to be shared with the community for players to access.

 

Base Class:Sorcerer

"My lineage was bourn out of the Planes of Fire. That flame courses through my veins and not even death will quench it."

-Valath, Fire Sorceress

 

Sorcerous Origin

Sorcerer Origin

Beginning at 1st level, you are deeply link to one of the elemental planes. This link is your sorcerer origin. When you choose one of these, spells that does that type of damage, you will add your Charisma modifier to. Also, you can use a sorcery point to change elemental damage of a spell that is not of your origin to that of your origin.

Elemental Origins

 

Choose one of the following elemental types:

 

 

 

That is it.

 As for the level one feature, it might help to say once per turn, to prevent EB shenanigans. And changing spells’ damage type is just transmuted spell metamagic.