Creating UserControl Like asp:CheckBoxList

 Hey,
I want to make a UserControl where you can add Controls into. It will be a FilterBar that you can toggle visible and invisible.
In there i have a div with the "content"
How would i archieve that i could use it like this:
1 <myUC:FilterBar ID="test" runat="server">
2 <asp:CheckBox ID="blablabla" runat="server" Text="BlaBlaBla" />
3 </myUC:FilterBar>
Is ther a Property i have to offer, or how can i do this? Maybe somebody got an example for m ...