How to dynamically add a row with textboxes inside a gridview in a modalpop window and show the same grid in parent page and save the data into database

Hi All...I am a newbie in this technology. Had implemented modal popup window part in my earlier assignments. But the current task which I stated in the subject is where I got strucked up. Straight to the point....
I had a Main webform where I would be providing end users with a hyperlink, which will in turn open a popup window on click. 
In the popup window, I need to provide an interface to add data inside a gridview like...Name, Age, Sex, Address and also provide feature to add more rows like if the users are multiple...then need to capture all the users information with above fields.
Then after clicking close button of the popup window, need to show the final list of gridview on the main page showing the same grid.
And finally submit the Main page gridview data along with other information in database.
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