Once you click on the 'Proceed to Next Step' button on the form, if it doesn't proceed, the main reason for this is that you haven't completed all the required/mandatory fields.  The required fields are marked with a red star and have 'required' entered in the field.  

The form will highlight the required fields that have been missed so scroll up and down the form and enter all the required information and then click on the 'Proceed to Next Step' button again.