Radio Button Data Binding-how?

 hi,
i have a DB that contains some tables.so i have a radio button group of tow radio button to display a field.
now how can i bind this radio button group to this field for updating  and insert a new record?
for more explain i brought a little of code below:
 in .aspx page i have:
 <asp:RadioButton ID="admin" runat="server" Checked="True" GroupName="membertype"
Text="admin" OnCheckedChanged="admin_CheckedChanged" /><br />
<asp:RadioButton ID="member" runat="server" GroupName="membertype" Text="member" /> 

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<asp:ControlParameter ControlID="membertype" Name="isadmin"   Type="string" PropertyName="text" />
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UpdateCommand="UPDATE UserManagement SET UserName = @UserName, Password = @Password, FullName = @FullName, Description = @Description, UserID = @UserID ,isadmin=@isadmin,usercitycode=@location  WHERE (UserID = @Original_UserID)"
 note that the type of the "isadmin" field is "nvarchar(50)"
thanks,
M.H.H