1. Click [New APL Class] at the top

2. Select "Object Export Plugin" for the function namespace, then complete the function name, remarks, and other information

3. Select a template - choose between using a template or an empty template, then click [Confirm]

4. Click [Save] to complete the function creation

5. Obtain the function apiname and submit for approval to bind the business function

Reference:
Configuring export function plugin (opens new window)