Selecting membership userid from a dropdownlist control to select a detailsview of a profile using sqltableprofileprovider

I set up a page where I can select a user to to look at their profile details. 

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"          DataSourceID="SqlDataSource1" DataTextField="UserName" DataValueField="UserId"     OnSelectedIndexChanged="Selection_Change">     </asp:DropDownList>