How can I add an extra field to my newsletter sign up form?

Hi all,
I’m trying to add an extra field to my newsletter sign up form.
Its at the bottom of this page
https://abbie-james.com/

The theme I’m using is Ira
https://themes.shopify.com/themes/ira/styles/active?surface_detail=ira&surface_inter_position=1&surface_intra_position=1&surface_type=search

Anyone know how I can add an additional field for people to add their names

TIA