How to insert the values into table in sqlserver

Hi,
 I have table like below in Sqlserver.
 QID UAnswer1  UAnswer2
 1  Null  2
 2  1  Null
 3  Null  2


I have to insert the values into table as For QID"4" user answer is 1 then It should save as for 4 Uanswer1 as "1" and Uanswer2 should be null. Like that i have to insert data into table. How can i achieve this?

Any one please help me........

Thanks & Regards,
 Nagaraju.