Passing parameter to SharePoint visual Studio WorkFlow

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SharePoint2010

Hi All,

I have created a state machine workflow on a SharePoint document library using visual studio 2010. The requirement of the project is, at the time workflow initiate it will send mail to the approvers to whom the task is assign. All the approvers email id and details is saved in a separate list. So I have added a method, findApprover() into create task Method invoking which returns the email ids of the approvers. I have tested it using the break point. Now my problem, once the break point comes to create task method invoking, it is excepting the file upload to document library by the user. Once I select the document and click OK button, the code is excepting the filter should work before it send mail to the approvers, but by that time user didn't select the filter. So my WorkflowProperties.item[ "<my column name>"] code returns null.
As per my understanding, I need to capture the event of the save button, in which user click after choosing the filter. Can anyone let me know what is the name of the save button which will change the properties of the list.

This is very urgent, any help is appreciable.

Thanks