module pool programming

Hi,

I am working on a module pool program.My requirement is,the o/p screen has many records.Besides each record there is a checkbox.If the user wants to change some of the field values in some records,then he clicks on the checkboxes of that particular records and when he clicks on the change button,control goes to update screen.In the update screen after the user changes the field values of some fields and clicks on the change button,all the changed values should get updated in the database table for all the checked records.

Now my doubt is

1)How can the changed values be updated in the database table for only the checked records

2)How can we capture the changed values in the update screen

If anyone worked on a similar kind of requirement pls send me the sample code of that.