Creating a new PHPExcel Object.

$this->PHPExcel = new PHPExcel();

Creating a new sheet:

$this->activeSheet = $this->PHPExcel->createSheet();

Getting the active Sheet:

$this->activeSheet = $this->PHPExcel->getActiveSheet();

Setting the active sheet:

$this->PHPExcel->setActiveSheetIndex(2);

Renaming a worksheet:

$this->activeSheet->setTitle($title);

Text can be added to a cell using setCellValue($colRow, $data)
$colRow - The column and row to write to (i.e. 'A2')
$data - The data to write

    $this->activeSheet->setCellValue($colRow, $data);       

    $this->activeSheet->setCellValueByColumnAndRow($column, $row, $data);  

    $this->activeSheet->setCellValueExplicit($coord, $value, $dataType);  
    $this->activeSheet->setCellValueExplicitByColumnAndRow($col, $row, $value, $dataType);  

A 2-dimensional array can be written to the current sheet usng fromArray($twoDimArray)

• $twoDimArray - the 2D array to be written
• $useWhenNull - what to use if there is a null value
• $topLeftCorner - where the top left corner should be.

$this->activeSheet->fromArray($sheet);  
$this->activeSheet->fromArray($sheet, "", $colRow);  

Or the array can be written manually by looping through the array and calling setCellValue

foreach($rows as $row => $columns) {
    foreach($columns as $column => $data) {
        $this->activeSheet->setCellValue($column.$row, $data);
    }
}

Setting column width
A single column:

$this->activeSheet->getColumnDimension($colString)->setWidth($width);

Default width for all columns on a sheet:

$this->activeSheet->getDefaultColumnDimension()->setWidth($width);

Auto size

$this->activeSheet->getColumnDimension("A")->setAutoSize(true);

$this->activeSheet->getStyle("B1")->getAlignment()->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_RIGHT);
$this->activeSheet->getStyle("B1:F1")->applyFromArray(array("font" => array( "bold" => true)));

Setting row height
A single row:

Default row height for an entire sheet:

$this->activeSheet
    ->getDefaultRowDimension()
    ->setRowHeight($height);

Setting default styles for the active sheet

$this->activeSheet
    ->getDefaultStyle()
    ->applyFromArray($this->defaultStyle);