If you need to add supplementary information to your form after you have submitted it, log into your home page. Under the heading 'Supplementary information', specify what section of the application from you wish to add to by selecting the title from the drop down box. Enter the additional information into the text box band click 'Save'. 

Note that this information will be available to the firm only in the section you specify and in the exact text format that you type. Supplementary information may be added up to the deadline for the options applied for.