C# - How To Connect GridView DataSource Over Webpart Class

i try to make myGridView Companent via using WebPArt you know it :

using System.Web.UI.WebControls.WebParts;
using System.Web.UI.WebControls;
using System.Web.UI;
namespace MyGridView
{
public class MyGridView : WebPart
{
GridView gv;
protected override void CreateChildControls()
{
gv = new GridView();
gv.CssClass = "tablestyle";
this.Controls.Add(gv);
}
}
}

i added this GridView on Toolbox. Every Thing is ok . İ want to add my own CSS design to my GridView. But if i drow this gridView from toolbox to aspx page. if i bind my datasource ; Datasource is not show himself.

Like that Main program:

protected void Page_Load(object sender, EventArgs e)
{
LoadData loaddata = new LoadData();
DataTable dt = loaddata.LoadSQL("conn", "sp_GetAllCategory");
MyGridView1.datas.... -----> i can not see DataSource why?
}

i want to see My GridView DataSource. if i write Binding datasource. MyGridView1.DataSource -----> i can not see DataSource why?