Faculty schedule time table using gridview in asp.net

Question

i am developing a faculty schedule time tbale using grid view in asp.net.

 Design screen as follows;



Coursename(DropDown)             Session                      Mon       Tue       Wed      Thu      Fri        sat
                         
 REO                                               1                             GS                                              
                                  (staff name in dropdown)
                                                      2                              VB                        
                                                      3                             UNNI                                      

 TAsco                                           1                               Ram   
                                                     2                               Sam  
                                                     3                               Gopi   

PFF                                               1                               GS                                              
                                                     2                               vintoh  
                                                     3                                RK

i want to use coursename in dropdown and staff name in drop down.

my conditon is Entered staff should not clash with course name.


 suppose staff is clash with course;  example as follows in design above see.
 
entered staff GS is clash with REO.

GS staff is taking class in monday 1 st session REO.that same staff GS should not take class PFF in the 1st session.becasue he is already taking class REO in the first session  on monday.

for the above condition how to write the code in asp.net using grid view.

when we select the dropdown in staff and press enter that staff should be displayed in the particlar cell postion in the run mode in that GridView,.

for the above one how to write the code.please help me.