Think yourself about your problem. You have 3 columns, then you need to store the data in 3 column format. You can try:
DataTable dt = new DataTable();
dt.Columns.Add("Name",typeof(string));
dt.Columns.Add("Size",typeof(string));
dt.Columns.Add("Brand",typeof(string));
Now add as many rows as you like:
dt.Rows.Add("1","10MB","SONY");
dt.Rows.Add("2","20MB","MOSERBAER");
dt.Rows.Add("3","30MB","HP");
Then bind the gridview:
Griddata.DataSource = dt.DefaultView;
Griddata.DataBind();