use reference of one table and get data from other table

Question

Hi!
i have two different tables. temptable, pictable.
the temptable contains all those usersname whos are online. and pictable contains pictures of all the users who are registered.
now i have an index.aspx page it contains gridview
what i want is to when the page loads it checks the temptable and take pictures of all those users that are present in temptable and show it in gridview.
please tell me how to do it.
thanks in advance