Assignment

Hello every body,
i want to place a button , and if user/ teacher clicks button it should open a new window. i want to place this code in grading system. Now teacher can directly selecting grade from drop down window. Instead of that i want to put a button. On clicking of that button it show open a new form in new window (i.e popup window ) where teacher will place the nos based on the assignment posted by user and it should automatically calcuate grade.
Thanks