This is more of a css question, but you should add the relevant styles\classes to your image. If you google how to lay things out in a grid you'll find better tutorials, but this is a basic way of doing it
<asp:Repeater id="rptSlides" runat="server" OnItemDataBound="rptSlides_ItemDataBound">
<HeaderTemplate>
<div>
</HeaderTemplate>
<ItemTemplate>
<asp:Image ID="myImage" runat="server" ImageUrl='<%#Eval("ImageUrl") %>' />
</ItemTemplate>
<FooterTemplate>
</div>
</FooterTemplate>
</asp:Repeater>
protected void Page_Load(object sender, EventArgs e)
{
rptSlides.DataSource = new List<MyData> {
new MyData { ImageUrl = "~/Images/pic1.png" },
new MyData { ImageUrl = "~/Images/pic2.png" },
new MyData { ImageUrl = "~/Images/pic3.png" },
new MyData { ImageUrl = "~/Images/pic4.png" },
new MyData { ImageUrl = "~/Images/pic5.png" }
};
rptSlides.DataBind();
}
protected void rptSlides_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
Image myImage = (Image)e.Item.FindControl("myImage");
myImage.Style["float"] = "left";
if (e.Item.ItemIndex % 2 == 0)
{
myImage.Style["clear"] = "both";
}
}
}