How to get out information from a DataGridView?
<p>I am working on program that calculate the <a href="http://en.wikipedia.org/wiki/GPA" rel="nofollow">GPA</a>s for university students in C#.</p>

<p>I have made a gridview that contains columns for each subject.  Its mark as letter and 
number.  After the user "student" insert his/her subject I want to let the user click a 
button that will get the mark and the number of the credit hours of each subject.  Calculate the GPA for the student and put the result in a textbox.</p>

<p>I am having trouble getting started.  Any advice for a good place to start?</p>
