fire click event of an asp button from jquery modal dialog to add a new row to a grid

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ASP.NET

jQuery

Gridview

Hello.
I have a grid view with several template fields (for drop-downs) which is working fine if I place it outside of the DIV what I use as modal dialog. Grid has onrowdatabound and OnRowDeleting events and additionally a button to add a new row to the grid. When I tried to move this grid to the Modal dialog the Add button stopped working. The click event is coded in code behind and it does not fire. I got an advise to use PostbackTrigger what didn't work for me. Another possibility was to use gridview.RowCommand event. But it handles all button related events inside a cell of a gridview whereas my button is outside of grid. Third: using jquery to force the postback on the button click using the __dopostback()and here I got confused since my experience with suff like that is not enough. On this site there is a link ezplaining how to use it
http://www.codeproject.com/Articles/667531/doPostBack-function
But I have no header or form tags on my page. It is on Master. Should I move the function __doPostBack on Master? And do Request.Form["__EVENTTARGET"] also there?
Can anyone help me to understand how I should handle it? Any help will be appreciated.