In the app, go to Help, open this tutorial and click Start from this template. It opens an option set with a priced text field.
In the preview, click that field, then open Price add-on.
Under Charge, pick Per character and enter the Price per character.
To include a few characters in the product price, enter how many under Free characters. Spaces are always free.
Under Products, choose where it shows, then click Save.
Still stuck?
Open the app in your Shopify admin, go to Help and click Chat with us, or email [email protected] with your store’s myshopify.com address.