Change gridview cell color and column color

hello....

ASP.net, C#.
I have a gridview with a crosstab access query.  

It is a attendance spreadsheet.
Name, 01 (Sun) 02 (Mon) 03 (Tue) ........ upto Date 15
The data is displaying pretty good, except that I would like to change some colors for:

1) I would like to go thru the headers (since I have not created them) - and check for "Sat" and "Sun" and change the Column color to beige.. (eg)

2) Then, I would like to go thru the rows and see if I have any data in the cells for employees, and if it is, I would like to color code them by each text in that cell.
O - off, V - Vacation, S-sick

so far, I have,

When I uploaded the data to the gridview, I also extract the column headers in a class.

This gives me all the column headers.
----------------------------------------------
public GridViewColumnHeadersList GetGridHeaders(OleDbDataReader dr)
        {
            GridViewColumnHeadersList gridviewcolumnheaderslist = new GridViewColumnHeadersList();
            if (DBReader.HasRows == true)
            {
                for (int i = 1; i <= DBReader.FieldCount-1; i++)
                {
                    if (DBReader.GetName(i) != "Employee Name")
                    {
                        gridviewcolumnheaderslist.Add(new GridViewColumnHeaders(DBReader.GetName(i)));
                    }

                }
            }
            return gridviewcolumnheaderslist;
        }

Then, in my form, I have create RowCreated
-----------------------------------------------------
protected void GridView1_RowCreated(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
        {
            ds.goThruGrid(e,GridView1);
        }

/// I am here now... .need help....
******************************
******************************
public void goThruGrid(System.Web.UI.WebControls.GridViewRowEventArgs e, GridView grd)
        {
            int x = 0;
            string sun = "Sun";
            string sat = "Sat";
            if (null != grdlist)
            {
                foreach (GridViewColumnHeaders c in grdlist)
                {
                    x = x + 1;
                    if (e.Row.RowType == DataControlRowType.Header)
                    {
                        foreach (TableCell Tc in e.Row.Cells)
                        {
                            if (Tc.Text == c.col_Name)
                            {
                                if ((c.col_Name.Substring(4,3) == sun) || (c.col_Name.Substring(4,3) == sun))
                                {
                                   
                                }

                            }
                            else
                            {

                            }