Creating posts and comments similar to Facebook - asp.net

Question

I need my own posts and comment on the page in my project, something similar to Facebook. I succesfully created posts by using sql table, sqldatasource and repeater. But I have a problem with comments.
I created sql table Comments, there is a column with Post ID. This is my code:
<asp:SqlDataSource ID="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:MotWebConnectionString %>"
SelectCommand="SELECT * FROM [Posts]
JOIN [Users] ON [Users].[UserName] = [Posts].[UserName]
JOIN [Comments] ON [Comments].[PostId] = [Posts].[PostId]
WHERE ([GroupId] = #GroupId) ">
<SelectParameters>
<asp:QueryStringParameter Name="GroupId" QueryStringField="id" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
asp:Repeater ID="Repeater1" runat="server" DataSourceID="SqlDataSource3" >
<ItemTemplate>
<table style="width: 100%;">
<tr>
<td width="10%">
<asp:Image ID="Image2" runat="server" Width="64px" Height="64px" ImageUrl='<%# Eval("ProfilePicture")%>' />
</td>
<td align="left" width="90%" >
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("UserName", "~/_/Profile.aspx?Username={0}")%>'><p><asp:Literal ID="Literal2" runat="server" Text='<%# Eval("Username")%>'></asp:Literal></p></asp:HyperLink>
</td>
</tr>
</table>
<asp:Literal ID="Literal3" runat="server" Text='<%# Eval("Text")%>'></asp:Literal>
<br />
<asp:Literal ID="Literal4" runat="server" Text='<%# Eval("CommentText")%>'></asp:Literal>
<asp:FormView ID="FormView2" runat="server" DataSourceID="SqlDataSource4" DefaultMode="Insert" >
<InsertItemTemplate>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" CommandName="Insert" />
</InsertItemTemplate>
</asp:FormView>
</ItemTemplate>
<SeparatorTemplate>
<br />
<br />
<br />
</SeparatorTemplate>
</asp:Repeater>
But it shows only posts, where is at least 1 comment and if there are more comments than 1, the posts is twice or more times on the page.
And another problem is, that I don't know how to insert right Post ID into the Comments table. It is probably by using Parameter...
My database schema (I did't know how to create it in SQL Management Studio, so it is in VS):
http://img685.imageshack.us/img685/1416/vstiekd.jpg
Please could anyone help me with this:
How to view right comments under the post and view also posts without any comment
How to insert the comment with right Post ID
I will be very thankfull for any kind of help