Alfresco's activiti add html file element in form -

Alfresco's activiti add html file element in form -

i want add together file upload html element in process definition's start in form.

<startevent id="start" name="start"> <extensionelements> <activiti:formproperty id="name" name="name" type="string" required="true" /> <activiti:formproperty id="emailaddress" name="email address" type="string" required="true" /> <activiti:formproperty id="income" name="income" type="long" required="true" /> <activiti:formproperty id="loanamount" name="loan amount" type="long" required="true" /> </extensionelements> </startevent>

i want add together file uploader @ end take file user , process further. tried using file info type of no use. please guide how can add together file element here.

thanks

alfresco activiti