Try below solution
in aspx code
<asp:DataList ID="dtlist" runat="server">
<ItemTemplate>
<asp:Image ID="imgsource" ImageUrl='<%# Eval("ImageUrl") %>' runat="server" />
</ItemTemplate>
</asp:DataList>
in code behind page
DataTable dt = new DataTable()
DataColumn dc = new DataColumn("ImageUrl");
dt.Columns.Add(dc);
ArrayList pics = new ArrayList();
string html;
DirectoryInfo dirs = new DirectoryInfo(Server.MapPath("~/images"));
html=dirs.GetFiles("*.jpg").Count().ToString ();
foreach (FileInfo s in dirs.GetFiles("*.jpg"))
{
DataRow dr = dt.NewRow();
dr[0] = s.Name;
dt.Rows.Add(dr);
}
dtlist.DataSource =dt;
dtlist .DataBind ();
}
hope this will help:)