Make separate text boxes for separate WordPress Custom Fields

Look at add_meta_box in the function reference. You can add a meta box in there, and within it add a number of input elements for your fields. You can also add multiple meta boxes if they’re unrelated elements.

If you want to look through the eStore theme, you’re probably looking for add_action('add_meta_boxes',...) (if it’s WordPress 3.0 or after), or add_action('admin_init',...)