updating a table through ALV

Hi all,

I have one requirement.

I need to display output using alv grid display.Next when somebody select the rows in the grid display and press a push button then the selected fields are updated in the ztable created.

How can i achieve this.

How to get a push button on the alv.

how to update the the table with the selected rows.

Please give some suggestions for this.

Thanks to all in advance.